Positive, nonzero integers within three units
Scientific notation expresses a quantity as the product of its significand with 10 raised to an integer exponent.
A number multiplied with its reciprocal is one.
The reciprocal of 81.
A numerical palindrome has the same value when all of its digits are reversed.
The number 81 is not a palindrome.
Not A Prime Number
A prime number is a positive integer that is divisible only by itself and one.
Eighty-one is a composite number with 5 total factors (including 1 and itself). See primes in Base 10 Decimal
Composites have more than just these two factors.
Eighty-one is a composite number with 5 total factors (including 1 and itself).
The number eighty-one has the following 1 prime factor:
The prime factorization of a positive integer is the unique list of prime factors together with their multiplicities
The number eighty-one in 35 different bases