21117604 has 12 divisors (see below), whose sum is σ = 39129804. Its totient is φ = 9937664.

The previous prime is 21117563. The next prime is 21117631. The reversal of 21117604 is 40671112.

It can be written as a sum of positive squares in 2 ways, for example, as 13838400 + 7279204 = 3720^2 + 2698^2 .

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, 155209 + ... + 155344.

It is an arithmetic number, because the mean of its divisors is an integer number (3260817).

Almost surely, 2^21117604 is an apocalyptic number.

It is an amenable number.

21117604 is a deficient number, since it is larger than the sum of its proper divisors (18012200).

21117604 is a wasteful number, since it uses less digits than its factorization.

21117604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 310574 (or 310572 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 21117604 is about 4595.3894285468. The cubic root of 21117604 is about 276.4064759175.

Adding to 21117604 its reverse (40671112), we get a palindrome (61788716).

The spelling of 21117604 in words is "twenty-one million, one hundred seventeen thousand, six hundred four".