81657925 has 12 divisors (see below), whose sum is σ = 102769216. Its totient is φ = 64350000.

The previous prime is 81657911. The next prime is 81657949. The reversal of 81657925 is 52975618.

It is not a de Polignac number, because 81657925 - 2²¹ = 79560773 is a prime.

It is a hoax number, since the sum of its digits (43) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 22701 + ... + 26050.

Almost surely, 2^81657925 is an apocalyptic number.

It is an amenable number.

81657925 is a deficient number, since it is larger than the sum of its proper divisors (21111291).

81657925 is a wasteful number, since it uses less digits than its factorization.

81657925 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48828 (or 48823 counting only the distinct ones).

The product of its digits is 151200, while the sum is 43.

The square root of 81657925 is about 9036.4774663582. The cubic root of 81657925 is about 433.8431852211.

The spelling of 81657925 in words is "eighty-one million, six hundred fifty-seven thousand, nine hundred twenty-five".