20644564 has 12 divisors (see below), whose sum is σ = 38029600. Its totient is φ = 9778968.

The previous prime is 20644537. The next prime is 20644627. The reversal of 20644564 is 46544602.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 135744 + ... + 135895.

Almost surely, 2^20644564 is an apocalyptic number.

It is an amenable number.

20644564 is a deficient number, since it is larger than the sum of its proper divisors (17385036).

20644564 is a wasteful number, since it uses less digits than its factorization.

20644564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 271662 (or 271660 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 31.

The square root of 20644564 is about 4543.6289461178. The cubic root of 20644564 is about 274.3270111328.

The spelling of 20644564 in words is "twenty million, six hundred forty-four thousand, five hundred sixty-four".