20864565 has 48 divisors (see below), whose sum is σ = 39761280. Its totient is φ = 10074240.

The previous prime is 20864539. The next prime is 20864573. The reversal of 20864565 is 56546802.

20864565 is a `hidden beast` number, since 2 + 0 + 8 + 645 + 6 + 5 = 666.

It is not a de Polignac number, because 20864565 - 2⁵ = 20864533 is a prime.

It is a congruent number.

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, 19135 + ... + 20195.

It is an arithmetic number, because the mean of its divisors is an integer number (828360).

Almost surely, 2^20864565 is an apocalyptic number.

It is an amenable number.

20864565 is a deficient number, since it is larger than the sum of its proper divisors (18896715).

20864565 is a wasteful number, since it uses less digits than its factorization.

20864565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1114 (or 1111 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 36.

The square root of 20864565 is about 4567.7746222860. The cubic root of 20864565 is about 275.2980350105.

The spelling of 20864565 in words is "twenty million, eight hundred sixty-four thousand, five hundred sixty-five".