81564525 has 36 divisors (see below), whose sum is σ = 166964512. Its totient is φ = 37285920.

The previous prime is 81564517. The next prime is 81564547. The reversal of 81564525 is 52546518.

81564525 is a `hidden beast` number, since 8 + 1 + 5 + 645 + 2 + 5 = 666.

It is not a de Polignac number, because 81564525 - 2³ = 81564517 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81564525.

It is a congruent number.

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, 24319 + ... + 27468.

Almost surely, 2^81564525 is an apocalyptic number.

It is an amenable number.

81564525 is an abundant number, since it is smaller than the sum of its proper divisors (85399987).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81564525 is a wasteful number, since it uses less digits than its factorization.

81564525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51810 (or 51802 counting only the distinct ones).

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

The square root of 81564525 is about 9031.3080447962. The cubic root of 81564525 is about 433.6777127637.

The spelling of 81564525 in words is "eighty-one million, five hundred sixty-four thousand, five hundred twenty-five".