21207304 has 16 divisors (see below), whose sum is σ = 40175100. Its totient is φ = 10493952.

The previous prime is 21207301. The next prime is 21207331. The reversal of 21207304 is 40370212.

It can be written as a sum of positive squares in 2 ways, for example, as 21178404 + 28900 = 4602^2 + 170^2 .

It is not an unprimeable number, because it can be changed into a prime (21207301) 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, 12889 + ... + 14440.

Almost surely, 2^21207304 is an apocalyptic number.

It is an amenable number.

21207304 is a deficient number, since it is larger than the sum of its proper divisors (18967796).

21207304 is a wasteful number, since it uses less digits than its factorization.

21207304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27432 (or 27428 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 19.

The square root of 21207304 is about 4605.1388686987. The cubic root of 21207304 is about 276.7972815954.

Adding to 21207304 its reverse (40370212), we get a palindrome (61577516).

The spelling of 21207304 in words is "twenty-one million, two hundred seven thousand, three hundred four".