20905664 has 28 divisors (see below), whose sum is σ = 44677584. Its totient is φ = 9648384.

The previous prime is 20905663. The next prime is 20905679. The reversal of 20905664 is 46650902.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a self number, because there is not a number n which added to its sum of digits gives 20905664.

It is not an unprimeable number, because it can be changed into a prime (20905663) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11732 + ... + 13395.

It is an arithmetic number, because the mean of its divisors is an integer number (1595628).

Almost surely, 2^20905664 is an apocalyptic number.

It is an amenable number.

20905664 is an abundant number, since it is smaller than the sum of its proper divisors (23771920).

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

20905664 is a wasteful number, since it uses less digits than its factorization.

20905664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25152 (or 25142 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 32.

The square root of 20905664 is about 4572.2712080540. The cubic root of 20905664 is about 275.4786770541.

The spelling of 20905664 in words is "twenty million, nine hundred five thousand, six hundred sixty-four".