21804408 has 48 divisors (see below), whose sum is σ = 60964800. Its totient is φ = 7032960.

The previous prime is 21804361. The next prime is 21804449. The reversal of 21804408 is 80440812.

21804408 is a `hidden beast` number, since 218 + 0 + 440 + 8 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2653 + ... + 7116.

It is an arithmetic number, because the mean of its divisors is an integer number (1270100).

Almost surely, 2^21804408 is an apocalyptic number.

It is an amenable number.

21804408 is an abundant number, since it is smaller than the sum of its proper divisors (39160392).

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

21804408 is a wasteful number, since it uses less digits than its factorization.

21804408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9812 (or 9805 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 27.

The square root of 21804408 is about 4669.5190330483. The cubic root of 21804408 is about 279.3710713680.

The spelling of 21804408 in words is "twenty-one million, eight hundred four thousand, four hundred eight".