81565425 has 36 divisors (see below), whose sum is σ = 147086940. Its totient is φ = 43205760.

The previous prime is 81565403. The next prime is 81565459. The reversal of 81565425 is 52456518.

It can be written as a sum of positive squares in 6 ways, for example, as 349281 + 81216144 = 591^2 + 9012^2 .

It is not a de Polignac number, because 81565425 - 2⁶ = 81565361 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81565425.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 34171 + ... + 36479.

Almost surely, 2^81565425 is an apocalyptic number.

It is an amenable number.

81565425 is a deficient number, since it is larger than the sum of its proper divisors (65521515).

81565425 is a wasteful number, since it uses less digits than its factorization.

81565425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2482 (or 2474 counting only the distinct ones).

The product of its digits is 48000, while the sum is 36.

The square root of 81565425 is about 9031.3578713281. The cubic root of 81565425 is about 433.6793078546.

The spelling of 81565425 in words is "eighty-one million, five hundred sixty-five thousand, four hundred twenty-five".