21968520 has 64 divisors (see below), whose sum is σ = 75323520. Its totient is φ = 5021184.

The previous prime is 21968509. The next prime is 21968543. The reversal of 21968520 is 2586912.

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, 12237 + ... + 13916.

It is an arithmetic number, because the mean of its divisors is an integer number (1176930).

Almost surely, 2^21968520 is an apocalyptic number.

21968520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21968520 is an abundant number, since it is smaller than the sum of its proper divisors (53355000).

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

21968520 is a wasteful number, since it uses less digits than its factorization.

21968520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26174 (or 26170 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 21968520 is about 4687.0587792346. The cubic root of 21968520 is about 280.0702204834.

The spelling of 21968520 in words is "twenty-one million, nine hundred sixty-eight thousand, five hundred twenty".