81572564 has 12 divisors (see below), whose sum is σ = 142826964. Its totient is φ = 40764864.

The previous prime is 81572527. The next prime is 81572573. The reversal of 81572564 is 46527518.

It can be written as a sum of positive squares in 2 ways, for example, as 27667600 + 53904964 = 5260^2 + 7342^2 .

It is a hoax number, since the sum of its digits (38) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5792 + ... + 14024.

It is an arithmetic number, because the mean of its divisors is an integer number (11902247).

Almost surely, 2^81572564 is an apocalyptic number.

It is an amenable number.

81572564 is a deficient number, since it is larger than the sum of its proper divisors (61254400).

81572564 is a wasteful number, since it uses less digits than its factorization.

81572564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10714 (or 10712 counting only the distinct ones).

The product of its digits is 67200, while the sum is 38.

The square root of 81572564 is about 9031.7530967138. The cubic root of 81572564 is about 433.6919600548.

The spelling of 81572564 in words is "eighty-one million, five hundred seventy-two thousand, five hundred sixty-four".