Number 81 facts
The odd number 81 is spelled 🔊, and written in words: eighty-one. The ordinal number 81st is said 🔊 and written as: eighty-first. Phone prefix +81 or 0081. The meaning of the number 81 in Maths: Is it Prime? Factorization and prime factors tree. The square root and cube root of 81. What is 81 in computer science, numerology, codes and images, photo art, writing and naming in other languages. Other interesting facts, videos, news related to 81. ‹‹ 80 82 ››
Interesting facts about the number 81
More photos ...Asteroids
- (81) Terpsichore is asteroid number 81. It was discovered by E. W. L. Tempel from Marseille Observatory on 9/30/1864.
Areas, mountains and surfaces
- The total area of Puerto Rico (main island) is 3,500 square miles (9,100 square km). Country Puerto Rico, insular area of the United States. 81th largest island in the world.
Distances
- There is a 81 miles (130 km) direct distance between Budta (Philippines) and Davao (Philippines).
- There is a 51 miles (81 km) direct distance between Erbil (Iraq) and Mosul (Iraq).
- There is a 81 miles (130 km) direct distance between Guangzhou (China) and Kowloon (Hong Kong).
- There is a 81 miles (130 km) direct distance between Hāora (India) and Khulna (Bangladesh).
- More distances ...
- There is a 81 miles (130 km) direct distance between Luoyang (China) and Pingdingshan (China).
- There is a 81 miles (129 km) direct distance between New York City (USA) and Philadelphia (USA).
- There is a 81 miles (129 km) direct distance between Santiago de los Caballeros (Dominican republic) and Santo Domingo (Dominican republic).
History and politics
- United Nations Security Council Resolution number 81, adopted 24 May 1950. General Assembly Resolution 258. Resolution text.
Literature
- The ISBN Group Identifier for books published in India. Example book: ISBN 81-7215-399-6 Joy Goswami (1995)
Mathematics
- 81 is the square of the sum of its digits.
Mobile and telephony
- Number 81 or +81 or 0081 is a dial the international call prefix for Japan. (00/+) is dial the international call prefix.
Science
- Thallium is the chemical element in the periodic table that has the symbol Tl and atomic number 81.
Sports
- The best athletes to wear number 81
Terrell Owens, NFL; Tim Brown, NFL; Dick "Night Train" Lane, NFL; Doug Atkins, NFL; Art Monk, NFL; Carl Eller, NFL
Tv, movies and cinematography
- Archive 81 | Official Trailer | Netflix
Please write us
If you know something interesting about the number 81 or any natural number (positive integer), please write to us.What is 81 in other units
The decimal (Arabic) number 81 converted to a Roman number is LXXXI.
Roman and decimal number conversions.
81 kilograms (kg) = 178.6 pounds (lbs)
81 pounds (lbs) = 36.7 kilograms (kg)
81 kilometers (km) equals to 50.331 miles (mi).
81 miles (mi) equals to 130.357 kilometers (km).
81 meters (m) equals to 130.357 feet (ft).
81 feet (ft) equals 24.689 meters (m).
81 centimeters (cm) equals to 31.9 inches (in).
81 inches (in) equals to 205.7 centimeters (cm).
81° Fahrenheit (°F) equals to 27.2° Celsius (°C)
81° Celsius (°C) equals to 177.8° Fahrenheit (°F)
81 Horsepower (hp) equals to 59.57 kilowatts (kW)
81 kilowatts (kW) equals to 110.14 horsepower (hp)
81 seconds equals to 1 minute, 21 seconds
81 minutes equals to 1 hour, 21 minutes
| The number 81 converted to a Mayan number is |
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| Decimal and Mayan number conversions. |
Weight conversion
81 kilograms (kg) = 178.6 pounds (lbs)
81 pounds (lbs) = 36.7 kilograms (kg)
Length conversion
81 kilometers (km) equals to 50.331 miles (mi).
81 miles (mi) equals to 130.357 kilometers (km).
81 meters (m) equals to 130.357 feet (ft).
81 feet (ft) equals 24.689 meters (m).
81 centimeters (cm) equals to 31.9 inches (in).
81 inches (in) equals to 205.7 centimeters (cm).
Temperature conversion
81° Fahrenheit (°F) equals to 27.2° Celsius (°C)
81° Celsius (°C) equals to 177.8° Fahrenheit (°F)
Power conversion
81 Horsepower (hp) equals to 59.57 kilowatts (kW)
81 kilowatts (kW) equals to 110.14 horsepower (hp)
Time conversion
(hours, minutes, seconds, days, weeks)81 seconds equals to 1 minute, 21 seconds
81 minutes equals to 1 hour, 21 minutes
Codes and images of the number 81
Number 81 morse code: ---.. .----Sign language for number 81:
Number 81 in braille:
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| Image (1) of the number | Image (2) of the number |
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Number 81 infographic
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Year 81 AD
- The Arch of Titus was constructed.
- Empress Deng Sui was born.
Gregorian, Hebrew, Islamic, Persian and Buddhist Year (Calendar)
Gregorian year 81 is Buddhist year 624.Buddhist year 81 is Gregorian year 462 a. C.
Gregorian year 81 is Islamic year -558 or -557.
Islamic year 81 is Gregorian year 700 or 701.
Gregorian year 81 is Persian year -542 or -541.
Persian year 81 is Gregorian 702 or 703.
Gregorian year 81 is Hebrew year 3841 or 3842.
Hebrew year 81 is Gregorian year 3679 a. C.
The Buddhist calendar is used in Sri Lanka, Cambodia, Laos, Thailand, and Burma. The Persian calendar is the official calendar in Iran and Afghanistan.
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Advanced math operations
Is Prime?
The number 81 is not a prime number. The closest prime numbers are 79, 83.
The 81st prime number in order is 419.
Factorization and factors (dividers)
The prime factors of 81 are 34 or 3^4 or 3**4
The factors of 81 are 1, 3, 9, 27, 81.
Total factors 5.
Sum of factors 121 (40).
Prime factor tree
Powers
The second power of 812 is 6.561.
The third power of 813 is 531.441.
Roots
The square root √81 is 9 exact square root.
The cube root of 3√81 is 4,326749.
Logarithms
The natural logarithm of No. ln 81 = loge 81 = 4,394449.
The logarithm to base 10 of No. log10 81 = 1,908485.
The Napierian logarithm of No. log1/e 81 = -4,394449.
Trigonometric functions
The cosine of 81 is 0,776686.The sine of 81 is -0,629888.
The tangent of 81 is -0,810994.
Number 81 in Computer Science
| Code type | Code value |
|---|---|
| Port 81/TCP | Torpark - Onion routing ORport |
| ASCII Html | Q Uppercase Q Q (ISO 8859-1 Characters) |
| Unix time | Unix time 81 is equal to Thursday Jan. 1, 1970, 12:01:21 a.m. GMT |
| IPv4, IPv6 | Number 81 internet address in dotted format v4 0.0.0.81, v6 ::51 |
| 81 Decimal | = 1010001 Binary |
| 81 Decimal | = 10000 Ternary |
| 81 Decimal | = 121 Octal |
| 81 Decimal | = 51 Hexadecimal (0x51 hex) |
| 81 BASE64 | ODE= |
| 81 MD5 | 43ec517d68b6edd3015b3edc9a11367b |
| 81 SHA1 | 1d513c0bcbe33b2e7440e5e14d0b22ef95c9d673 |
| 81 SHA224 | 0334eec4a00b1fbc7fcf4225707609c926a23a8c77b4def29fd71006 |
| 81 SHA256 | 5316ca1c5ddca8e6ceccfce58f3b8540e540ee22f6180fb89492904051b3d531 |
| 81 SHA384 | 456d0ef673c9975197784ab352c2d9a9801185cdec3b1c449482b13d4b5bc9220735b37747fee9feaebbc5d1c3286fd0 |
| More SHA codes related to the number 81 ... | |
If you know something interesting about the 81 number that you did not find on this page, do not hesitate to write us here.
Numerology 81
According to Wikipedia, numerology is based on faith, yet many people seek the meaning of the number 81 from a numerological perspective.
More about numerology 81 ...
More about numerology 81 ...
№ 81 in other languages
How to say or write the number eighty-one in Spanish, German, French and other languages.
| Spanish: | 🔊 (número 81) | ochenta y uno |
| German: | 🔊 (Nummer 81) | einundachtzig |
| French: | 🔊 (nombre 81) | quatre-vingt-un |
| Portuguese: | 🔊 (número 81) | oitenta e um |
| Hindi: | 🔊 (संख्या 81) | इक्यासी |
| Chinese: | 🔊 (数 81) | 八十一 |
| Arabian: | 🔊 (عدد 81) | واحد و ثمانون |
| Czech: | 🔊 (číslo 81) | osmdesát jedna |
| Korean: | 🔊 (번호 81) | 팔십일 |
| Danish: | 🔊 (nummer 81) | enogfirs |
| Hebrew: | (מספר 81) | שמונים ואחת |
| Dutch: | 🔊 (nummer 81) | eenentachtig |
| Japanese: | 🔊 (数 81) | 八十一 |
| Indonesian: | 🔊 (jumlah 81) | delapan puluh satu |
| Italian: | 🔊 (numero 81) | ottantuno |
| Norwegian: | 🔊 (nummer 81) | åtti-en |
| Polish: | 🔊 (liczba 81) | osiemdziesiąt jeden |
| Russian: | 🔊 (номер 81) | восемьдесят один |
| Turkish: | 🔊 (numara 81) | seksenbir |
| Thai: | 🔊 (จำนวน 81) | แปดสิบเอ็ด |
| Ukrainian: | 🔊 (номер 81) | вісімдесят один |
| Vietnamese: | 🔊 (con số 81) | tám mươi mốt |
| Other languages ... | ||
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Frequently asked questions about the number 81
How do you write the number 81 in words?
81 can be written as "eighty-one".
Number 81 in News
| NyTimes: Costa Rica Violated Rights of 81 Migrant Children Deported by U.S., Lawsuit Says
A legal challenge filed Thursday aims to encourage Central American countries to push back against the Trump administration’s immigration policies. April 18, 2025 |
| NyTimes: Rabbi Shmuel Butman, 81, a Brooklyn Voice of Ultra-Orthodox Jews, Is Dead
He was the public face of the Chabad-Lubavitch sect during the Crown Heights riots in 1991 and for decades lit its giant menorah in Manhattan every Hanukkah. Aug. 14, 2024 |
| The Sydney Morning Herald: Rubble from 81 million kilometres away: Capsule carrying asteroid secrets lands on Earth
Asteroid samples fetched from deep space have parachuted into the Utah desert to cap a seven-year journey. Sept. 25, 2023 |
| France24: Saudi Arabia executes record 81 people in one day for terrorism-related offences
Saudi Arabia said Saturday it had executed a record 81 people in one day for terrorism-related offences, exceeding the total number killed last year and sparking criticism from rights activists. March 13, 2022 |
| The Sydney Morning Herald: Mass execution in Saudi Arabia as 81 people put to death
The executions come at a time of heightened concern over Saudi Arabia’s human rights record, but also as the West scrambles to replace its dependence on Russian oil. March 13, 2022 |