20659640 has 32 divisors (see below), whose sum is σ = 47986560. Its totient is φ = 7996800.

The previous prime is 20659627. The next prime is 20659697. The reversal of 20659640 is 4695602.

It is a junction number, because it is equal to n+sod(n) for n = 20659597 and 20659606.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7091 + ... + 9570.

It is an arithmetic number, because the mean of its divisors is an integer number (1499580).

Almost surely, 2^20659640 is an apocalyptic number.

20659640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20659640 is an abundant number, since it is smaller than the sum of its proper divisors (27326920).

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

20659640 is a wasteful number, since it uses less digits than its factorization.

20659640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16703 (or 16699 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 32.

The square root of 20659640 is about 4545.2876696640. The cubic root of 20659640 is about 274.3937720114.

The spelling of 20659640 in words is "twenty million, six hundred fifty-nine thousand, six hundred forty".