20812640 has 24 divisors (see below), whose sum is σ = 49170240. Its totient is φ = 8324992.

The previous prime is 20812639. The next prime is 20812699. The reversal of 20812640 is 4621802.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64880 + ... + 65199.

It is an arithmetic number, because the mean of its divisors is an integer number (2048760).

Almost surely, 2^20812640 is an apocalyptic number.

20812640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20812640 is an abundant number, since it is smaller than the sum of its proper divisors (28357600).

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

20812640 is a wasteful number, since it uses less digits than its factorization.

20812640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130094 (or 130086 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 20812640 is about 4562.0872416033. The cubic root of 20812640 is about 275.0694700524.

The spelling of 20812640 in words is "twenty million, eight hundred twelve thousand, six hundred forty".