21309304 has 16 divisors (see below), whose sum is σ = 40095720. Its totient is φ = 10617120.

The previous prime is 21309289. The next prime is 21309319. The reversal of 21309304 is 40390312.

It is an interprime number because it is at equal distance from previous prime (21309289) and next prime (21309319).

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, 2202 + ... + 6889.

Almost surely, 2^21309304 is an apocalyptic number.

It is an amenable number.

21309304 is a deficient number, since it is larger than the sum of its proper divisors (18786416).

21309304 is a wasteful number, since it uses less digits than its factorization.

21309304 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9390 (or 9386 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 22.

The square root of 21309304 is about 4616.2001689701. The cubic root of 21309304 is about 277.2403393114.

Adding to 21309304 its reverse (40390312), we get a palindrome (61699616).

The spelling of 21309304 in words is "twenty-one million, three hundred nine thousand, three hundred four".