81330857 has 2 divisors, whose sum is σ = 81330858. Its totient is φ = 81330856.

The previous prime is 81330827. The next prime is 81330863. The reversal of 81330857 is 75803318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61089856 + 20241001 = 7816^2 + 4499^2 .

It is a cyclic number.

It is not a de Polignac number, because 81330857 - 2⁶ = 81330793 is a prime.

It is a super-2 number, since 2×81330857² = 13229416600708898, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81330817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40665428 + 40665429.

It is an arithmetic number, because the mean of its divisors is an integer number (40665429).

Almost surely, 2^81330857 is an apocalyptic number.

It is an amenable number.

81330857 is a deficient number, since it is larger than the sum of its proper divisors (1).

81330857 is an equidigital number, since it uses as much as digits as its factorization.

81330857 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20160, while the sum is 35.

The square root of 81330857 is about 9018.3622127302. The cubic root of 81330857 is about 433.2631798990.

The spelling of 81330857 in words is "eighty-one million, three hundred thirty thousand, eight hundred fifty-seven".