20989664 has 12 divisors (see below), whose sum is σ = 41323464. Its totient is φ = 10494816.

The previous prime is 20989651. The next prime is 20989711. The reversal of 20989664 is 46698902.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors.

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, 327932 + ... + 327995.

It is an arithmetic number, because the mean of its divisors is an integer number (3443622).

Almost surely, 2^20989664 is an apocalyptic number.

It is an amenable number.

20989664 is a deficient number, since it is larger than the sum of its proper divisors (20333800).

20989664 is an equidigital number, since it uses as much as digits as its factorization.

20989664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 655937 (or 655929 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 44.

The square root of 20989664 is about 4581.4478060980. The cubic root of 20989664 is about 275.8471463365.

The spelling of 20989664 in words is "twenty million, nine hundred eighty-nine thousand, six hundred sixty-four".