21808204 has 24 divisors (see below), whose sum is σ = 42109200. Its totient is φ = 9799680.

The previous prime is 21808177. The next prime is 21808217. The reversal of 21808204 is 40280812.

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, 1132 + ... + 6700.

It is an arithmetic number, because the mean of its divisors is an integer number (1754550).

Almost surely, 2^21808204 is an apocalyptic number.

It is an amenable number.

21808204 is a deficient number, since it is larger than the sum of its proper divisors (20300996).

21808204 is a wasteful number, since it uses less digits than its factorization.

21808204 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5673 (or 5671 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 25.

The square root of 21808204 is about 4669.9254812042. The cubic root of 21808204 is about 279.3872826321.

The spelling of 21808204 in words is "twenty-one million, eight hundred eight thousand, two hundred four".