21604992 has 32 divisors (see below), whose sum is σ = 57389280. Its totient is φ = 7201536.

The previous prime is 21604987. The next prime is 21604993. The reversal of 21604992 is 29940612.

It is a tau number, because it is divible by the number of its divisors (32).

It is not an unprimeable number, because it can be changed into a prime (21604993) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27748 + ... + 28515.

It is an arithmetic number, because the mean of its divisors is an integer number (1793415).

Almost surely, 2^21604992 is an apocalyptic number.

It is an amenable number.

21604992 is an abundant number, since it is smaller than the sum of its proper divisors (35784288).

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

21604992 is an equidigital number, since it uses as much as digits as its factorization.

21604992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56280 (or 56268 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 33.

The square root of 21604992 is about 4648.1170381134. The cubic root of 21604992 is about 278.5167828192.

The spelling of 21604992 in words is "twenty-one million, six hundred four thousand, nine hundred ninety-two".