81912497957 has 16 divisors (see below), whose sum is σ = 87799464000. Its totient is φ = 76186543104.

The previous prime is 81912497941. The next prime is 81912497971. The reversal of 81912497957 is 75979421918.

It is a cyclic number.

It is not a de Polignac number, because 81912497957 - 2⁴ = 81912497941 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81912497957.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81912497257) 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 15 ways as a sum of consecutive naturals, for example, 819269 + ... + 913797.

It is an arithmetic number, because the mean of its divisors is an integer number (5487466500).

Almost surely, 2^81912497957 is an apocalyptic number.

It is an amenable number.

81912497957 is a deficient number, since it is larger than the sum of its proper divisors (5886966043).

81912497957 is a wasteful number, since it uses less digits than its factorization.

81912497957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95380.

The product of its digits is 11430720, while the sum is 62.

The spelling of 81912497957 in words is "eighty-one billion, nine hundred twelve million, four hundred ninety-seven thousand, nine hundred fifty-seven".