81537690567 has 32 divisors (see below), whose sum is σ = 111631855104. Its totient is φ = 52923024000.

The previous prime is 81537690557. The next prime is 81537690593. The reversal of 81537690567 is 76509673518.

It is not a de Polignac number, because 81537690567 - 2²² = 81533496263 is a prime.

It is a Smith number, since the sum of its digits (57) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81537690557) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8535888 + ... + 8545434.

It is an arithmetic number, because the mean of its divisors is an integer number (3488495472).

Almost surely, 2^81537690567 is an apocalyptic number.

81537690567 is a deficient number, since it is larger than the sum of its proper divisors (30094164537).

81537690567 is a wasteful number, since it uses less digits than its factorization.

81537690567 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10119.

The product of its (nonzero) digits is 9525600, while the sum is 57.

The spelling of 81537690567 in words is "eighty-one billion, five hundred thirty-seven million, six hundred ninety thousand, five hundred sixty-seven".