Number 81

Names of 81

Nominal 81
Cardinal eighty-one
Ordinal 81st
This number as US currency eighty-one dollars

Properties (and some facts) of 81

Is 81 an odd number? 81 is an odd number
Is 81 an even number? 81 is NOT an even number
Is 81 a palindrome? 81 is NOT a palindrome number
Is 81 a triangle number? 81 is NOT a triangle number

81 in other Bases

Base 2 (Binary) 10100012
Base 3 (Ternary) 100003
Base 4 (Quaternary) 11014
Base 5 (Quinary) 3115
Base 6 (Senary) 2136
Base 8 (Octal) 1218
Base 12 (Duodecimal) 6912
Base 16 (Hexadecimal) 5116
Base 20 (Vigesimal) 4120

Primes and Factors tests for 81

Is 81 a Prime Number? 81 is NOT a prime
Is 81 a perfect number? 81 is NOT a perfect number
Is 81 a Mersenne Prime? 81 is NOT a Mersenne prime
Is 81 a Fermat Prime? 81 is NOT a Fermat prime
Is 81 a Fibonacci Prime? 81 is NOT a Fibonacci prime
Is 81 a Partition Prime? 81 is NOT a Partition prime
Is 81 a Pell Prime? 81 is NOT a Pell prime
Prime Factors Prime factors of 81

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81 in other Numerals

81 in Roman Numeral LXXXI
81 in Chinese Numeral 捌拾壹
81 in Egyptian Numeral 𓎍𓏺
81 in Babylonian Numeral 1   21  

Roots and stuff for 81

Is 81 a square number? 81 is a square number
Is 81 a cube number? 81 is NOT a cube number
Square root of the number 81 9
Cube root of the number 81 4.3267487109222

Recreational math for 81

Number 81 reversed 18
Sum of the digits 9
No of digits 2