81957044025 has 48 divisors (see below), whose sum is σ = 150665257600. Its totient is φ = 43679321280.

The previous prime is 81957044017. The next prime is 81957044041. The reversal of 81957044025 is 52044075918.

81957044025 is a `hidden beast` number, since 8 + 19 + 570 + 4 + 40 + 25 = 666.

It is not a de Polignac number, because 81957044025 - 2³ = 81957044017 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 922092 + ... + 1007058.

Almost surely, 2^81957044025 is an apocalyptic number.

It is an amenable number.

81957044025 is a deficient number, since it is larger than the sum of its proper divisors (68708213575).

81957044025 is a wasteful number, since it uses less digits than its factorization.

81957044025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86415 (or 86404 counting only the distinct ones).

The product of its (nonzero) digits is 403200, while the sum is 45.

The spelling of 81957044025 in words is "eighty-one billion, nine hundred fifty-seven million, forty-four thousand, twenty-five".