20640636 has 48 divisors (see below), whose sum is σ = 53760000. Its totient is φ = 6848496.

The previous prime is 20640617. The next prime is 20640647. The reversal of 20640636 is 63604602.

20640636 is a `hidden beast` number, since 20 + 6 + 4 + 0 + 636 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41115 + ... + 41613.

It is an arithmetic number, because the mean of its divisors is an integer number (1120000).

Almost surely, 2^20640636 is an apocalyptic number.

It is an amenable number.

20640636 is an abundant number, since it is smaller than the sum of its proper divisors (33119364).

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

20640636 is a wasteful number, since it uses less digits than its factorization.

20640636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 895 (or 887 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 27.

The square root of 20640636 is about 4543.1966719481. The cubic root of 20640636 is about 274.3096114782.

The spelling of 20640636 in words is "twenty million, six hundred forty thousand, six hundred thirty-six".