81508057679 has 4 divisors (see below), whose sum is σ = 81533460720. Its totient is φ = 81482654640.

The previous prime is 81508057669. The next prime is 81508057703. The reversal of 81508057679 is 97675080518.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81508057679 - 2²⁴ = 81491280463 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81508057619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12696707 + ... + 12703124.

It is an arithmetic number, because the mean of its divisors is an integer number (20383365180).

Almost surely, 2^81508057679 is an apocalyptic number.

81508057679 is a deficient number, since it is larger than the sum of its proper divisors (25403041).

81508057679 is a wasteful number, since it uses less digits than its factorization.

81508057679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25403040.

The product of its (nonzero) digits is 4233600, while the sum is 56.

The spelling of 81508057679 in words is "eighty-one billion, five hundred eight million, fifty-seven thousand, six hundred seventy-nine".