20640660 has 48 divisors (see below), whose sum is σ = 60310656. Its totient is φ = 5264512.

The previous prime is 20640647. The next prime is 20640667. The reversal of 20640660 is 6604602.

It is a self number, because there is not a number n which added to its sum of digits gives 20640660.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20640667) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6099 + ... + 8858.

It is an arithmetic number, because the mean of its divisors is an integer number (1256472).

Almost surely, 2^20640660 is an apocalyptic number.

20640660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20640660 is an abundant number, since it is smaller than the sum of its proper divisors (39669996).

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

20640660 is a wasteful number, since it uses less digits than its factorization.

20640660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14992 (or 14990 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 24.

The square root of 20640660 is about 4543.1993132593. The cubic root of 20640660 is about 274.3097177964.

The spelling of 20640660 in words is "twenty million, six hundred forty thousand, six hundred sixty".