21604208 has 20 divisors (see below), whose sum is σ = 42750240. Its totient is φ = 10571904.

The previous prime is 21604181. The next prime is 21604213. The reversal of 21604208 is 80240612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13613 + ... + 15116.

It is an arithmetic number, because the mean of its divisors is an integer number (2137512).

Almost surely, 2^21604208 is an apocalyptic number.

It is an amenable number.

21604208 is a deficient number, since it is larger than the sum of its proper divisors (21146032).

21604208 is a wasteful number, since it uses less digits than its factorization.

21604208 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28784 (or 28778 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 21604208 is about 4648.0327021225. The cubic root of 21604208 is about 278.5134138479.

It can be divided in two parts, 21604 and 208, that added together give a palindrome (21812).

The spelling of 21604208 in words is "twenty-one million, six hundred four thousand, two hundred eight".