21621604 has 12 divisors (see below), whose sum is σ = 38718064. Its totient is φ = 10559304.

The previous prime is 21621577. The next prime is 21621629. The reversal of 21621604 is 40612612.

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 3 ways as a sum of consecutive naturals, for example, 62682 + ... + 63025.

Almost surely, 2^21621604 is an apocalyptic number.

It is an amenable number.

21621604 is a deficient number, since it is larger than the sum of its proper divisors (17096460).

21621604 is a wasteful number, since it uses less digits than its factorization.

21621604 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125754 (or 125752 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 21621604 is about 4649.9036549159. The cubic root of 21621604 is about 278.5881480463.

The spelling of 21621604 in words is "twenty-one million, six hundred twenty-one thousand, six hundred four".