21616204 has 12 divisors (see below), whose sum is σ = 38448928. Its totient is φ = 10630800.

The previous prime is 21616201. The next prime is 21616211. The reversal of 21616204 is 40261612.

It is not an unprimeable number, because it can be changed into a prime (21616201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44052 + ... + 44539.

Almost surely, 2^21616204 is an apocalyptic number.

It is an amenable number.

21616204 is a deficient number, since it is larger than the sum of its proper divisors (16832724).

21616204 is a wasteful number, since it uses less digits than its factorization.

21616204 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88656 (or 88654 counting only the distinct ones).

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

The square root of 21616204 is about 4649.3229614644. The cubic root of 21616204 is about 278.5649536330.

Adding to 21616204 its reverse (40261612), we get a palindrome (61877816).

It can be divided in two parts, 21 and 616204, that added together give a square (616225 = 785²).

The spelling of 21616204 in words is "twenty-one million, six hundred sixteen thousand, two hundred four".