21668304 has 40 divisors (see below), whose sum is σ = 63974080. Its totient is φ = 6190848.

The previous prime is 21668299. The next prime is 21668327. The reversal of 21668304 is 40386612.

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, 31909 + ... + 32580.

It is an arithmetic number, because the mean of its divisors is an integer number (1599352).

Almost surely, 2^21668304 is an apocalyptic number.

21668304 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21668304 is an abundant number, since it is smaller than the sum of its proper divisors (42305776).

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

21668304 is a wasteful number, since it uses less digits than its factorization.

21668304 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64507 (or 64501 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 21668304 is about 4654.9225557468. The cubic root of 21668304 is about 278.7885758379.

The spelling of 21668304 in words is "twenty-one million, six hundred sixty-eight thousand, three hundred four".