20856664 has 8 divisors (see below), whose sum is σ = 39106260. Its totient is φ = 10428328.

The previous prime is 20856629. The next prime is 20856679. The reversal of 20856664 is 46665802.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1303534 + ... + 1303549.

Almost surely, 2^20856664 is an apocalyptic number.

It is an amenable number.

20856664 is a deficient number, since it is larger than the sum of its proper divisors (18249596).

20856664 is a wasteful number, since it uses less digits than its factorization.

20856664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2607089 (or 2607085 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 37.

The square root of 20856664 is about 4566.9096772325. The cubic root of 20856664 is about 275.2632806412.

The spelling of 20856664 in words is "twenty million, eight hundred fifty-six thousand, six hundred sixty-four".