21399304 has 8 divisors (see below), whose sum is σ = 40123710. Its totient is φ = 10699648.

The previous prime is 21399299. The next prime is 21399307. The reversal of 21399304 is 40399312.

It can be written as a sum of positive squares in only one way, i.e., 21178404 + 220900 = 4602^2 + 470^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (21399307) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1337449 + ... + 1337464.

Almost surely, 2^21399304 is an apocalyptic number.

It is an amenable number.

21399304 is a deficient number, since it is larger than the sum of its proper divisors (18724406).

21399304 is a wasteful number, since it uses less digits than its factorization.

21399304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2674919 (or 2674915 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 31.

The square root of 21399304 is about 4625.9381751165. The cubic root of 21399304 is about 277.6300999677.

The spelling of 21399304 in words is "twenty-one million, three hundred ninety-nine thousand, three hundred four".