# Number 81

Number 81 spell 🔊, write in words: eighty-one . Ordinal number 81th is said 🔊 and write: eighty-first. Phone prefix +81 or 0081. The meaning of number 81 in Maths: Is Prime? Factorization and dividers. The square root and cube root of 81. The meaning in computer science, numerology, codes and images, writing and naming in other languages, other interesting facts, news.

## Useful information about number 81

The decimal (Arabic) number 81 converted to a Roman number is LXXXI. Roman and decimal number conversions.
 The number 81 converted to a Mayan number is Decimal and Mayan number conversions.

#### Weight conversion

81 kilograms (kg) = 178.6 pounds (lb)
81 pounds (lb) = 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:  Images of the number Image (1) of the number Image (2) of the number  There is no copyright for these images. Number 81 infographic. More images, other sizes, codes and colors ...

### Photo of number 81 ### 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 official in Iran and Afghanistan.

## Share in social networks ## Mathematics of no. 81

### Multiplications

#### Multiplication table of 81

81 multiplied by two equals 162 (81 x 2 = 162).
81 multiplied by three equals 243 (81 x 3 = 243).
81 multiplied by four equals 324 (81 x 4 = 324).
81 multiplied by five equals 405 (81 x 5 = 405).
81 multiplied by six equals 486 (81 x 6 = 486).
81 multiplied by seven equals 567 (81 x 7 = 567).
81 multiplied by eight equals 648 (81 x 8 = 648).
81 multiplied by nine equals 729 (81 x 9 = 729).
show multiplications by 6, 7, 8, 9 ...

### Fractions: decimal fraction and common fraction

#### Fraction table of 81

Half of 81 is 40,5 (81 / 2 = 40,5 = 40 1/2).
One third of 81 is 27 (81 / 3 = 27).
One quarter of 81 is 20,25 (81 / 4 = 20,25 = 20 1/4).
One fifth of 81 is 16,2 (81 / 5 = 16,2 = 16 1/5).
One sixth of 81 is 13,5 (81 / 6 = 13,5 = 13 1/2).
One seventh of 81 is 11,5714 (81 / 7 = 11,5714 = 11 4/7).
One eighth of 81 is 10,125 (81 / 8 = 10,125 = 10 1/8).
One ninth of 81 is 9 (81 / 9 = 9).
show fractions by 6, 7, 8, 9 ...

### Calculator

 81

#### Is Prime?

The number 81 is not a prime number. The closest prime numbers are 79, 83.
81th prime number in order is 419.

#### Factorization and dividers

Factorization 3 * 3 * 3 * 3 = 81
Divisors of number 81 are 1 , 3 , 9 , 27 , 81
Total Divisors 5.
Sum of Divisors 121.

#### Powers

The second power of 812 is 6.561.
The third power of 813 is 531.441.

#### Roots

The cube root of 381 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.

### Properties of the number 81

Is a Friedman number: No
Is a Fibonacci number: No
Is a Bell number: No
Is a palindromic number: No
Is a pentagonal number: No
Is a perfect number: No

## Number 81 in Computer Science

Code typeCode value
Port 81/TCPTorpark - Onion routing ORport
Ascii81 ascii is character Q
Unix timeUnix time 81 is equal to Thursday Jan. 1, 1970, 12:01:21 a.m. GMT
IPv4, IPv6Number 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 BASE64ODE=
81 MD543ec517d68b6edd3015b3edc9a11367b
81 SHA11d513c0bcbe33b2e7440e5e14d0b22ef95c9d673
81 SHA2240334eec4a00b1fbc7fcf4225707609c926a23a8c77b4def29fd71006
81 SHA2565316ca1c5ddca8e6ceccfce58f3b8540e540ee22f6180fb89492904051b3d531
81 SHA384456d0ef673c9975197784ab352c2d9a9801185cdec3b1c449482b13d4b5bc9220735b37747fee9feaebbc5d1c3286fd0
More SHA codes related to the number 81 ...

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## Numerology 81

### The meaning of the number 8 (eight), numerology 8

Character frequency 8: 1

The number eight (8) is the sign of organization, perseverance and control of energy to produce material and spiritual achievements. It represents the power of realization, abundance in the spiritual and material world. Sometimes it denotes a tendency to sacrifice but also to be unscrupulous.
More about the meaning of the number 8 (eight), numerology 8 ...

### The meaning of the number 1 (one), numerology 1

Character frequency 1: 1

Number one (1) came to develop or balance creativity, independence, originality, self-reliance and confidence in the world. It reflects power, creative strength, quick mind, drive and ambition. It is the sign of individualistic and aggressive nature.
More about the meaning of the number 1 (one), numerology 1 ...

## Interesting facts about the number 81

### 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 between cities

• 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).
• 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).

### 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

## Number 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: 🔊 (Anzahl 81) einundachtzig French: 🔊 (nombre 81) quatre-vingt-un Portuguese: 🔊 (número 81) oitenta e um 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) שמנים ואחד 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) вiсiмдесят одна Vietnamese: 🔊 (con số 81) tám mươi mốt Other languages ...

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