21030304 has 12 divisors (see below), whose sum is σ = 41403474. Its totient is φ = 10515136.

The previous prime is 21030301. The next prime is 21030313. The reversal of 21030304 is 40303012.

It can be written as a sum of positive squares in only one way, i.e., 19820304 + 1210000 = 4452^2 + 1100^2 .

It is not an unprimeable number, because it can be changed into a prime (21030301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 328567 + ... + 328630.

Almost surely, 2^21030304 is an apocalyptic number.

It is an amenable number.

21030304 is a deficient number, since it is larger than the sum of its proper divisors (20373170).

21030304 is an equidigital number, since it uses as much as digits as its factorization.

21030304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 657207 (or 657199 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 13.

The square root of 21030304 is about 4585.8809404519. The cubic root of 21030304 is about 276.0250624864.

Adding to 21030304 its reverse (40303012), we get a palindrome (61333316).

The spelling of 21030304 in words is "twenty-one million, thirty thousand, three hundred four".