21553604 has 12 divisors (see below), whose sum is σ = 37769004. Its totient is φ = 10762464.

The previous prime is 21553531. The next prime is 21553613. The reversal of 21553604 is 40635512.

It can be written as a sum of positive squares in 2 ways, for example, as 5569600 + 15984004 = 2360^2 + 3998^2 .

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, 254 + ... + 6570.

It is an arithmetic number, because the mean of its divisors is an integer number (3147417).

Almost surely, 2^21553604 is an apocalyptic number.

It is an amenable number.

21553604 is a deficient number, since it is larger than the sum of its proper divisors (16215400).

21553604 is a wasteful number, since it uses less digits than its factorization.

21553604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7174 (or 7172 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 26.

The square root of 21553604 is about 4642.5859173525. The cubic root of 21553604 is about 278.2957878607.

The spelling of 21553604 in words is "twenty-one million, five hundred fifty-three thousand, six hundred four".