20646639 has 12 divisors (see below), whose sum is σ = 32117176. Its totient is φ = 12705552.

The previous prime is 20646631. The next prime is 20646667. The reversal of 20646639 is 93664602.

20646639 is a `hidden beast` number, since 2 + 0 + 646 + 6 + 3 + 9 = 666.

It is not a de Polignac number, because 20646639 - 2³ = 20646631 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20646631) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 88117 + ... + 88350.

Almost surely, 2^20646639 is an apocalyptic number.

20646639 is a deficient number, since it is larger than the sum of its proper divisors (11470537).

20646639 is a wasteful number, since it uses less digits than its factorization.

20646639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 176486 (or 176483 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 36.

The square root of 20646639 is about 4543.8572820897. The cubic root of 20646639 is about 274.3362017600.

The spelling of 20646639 in words is "twenty million, six hundred forty-six thousand, six hundred thirty-nine".