21002304 has 28 divisors (see below), whose sum is σ = 55569104. Its totient is φ = 7000704.

The previous prime is 21002299. The next prime is 21002323. The reversal of 21002304 is 40320012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a self number, because there is not a number n which added to its sum of digits gives 21002304.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 54502 + ... + 54885.

Almost surely, 2^21002304 is an apocalyptic number.

21002304 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21002304 is an abundant number, since it is smaller than the sum of its proper divisors (34566800).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21002304 is a wasteful number, since it uses less digits than its factorization.

21002304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109402 (or 109392 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 12.

The square root of 21002304 is about 4582.8270750706. The cubic root of 21002304 is about 275.9025070490.

Adding to 21002304 its reverse (40320012), we get a palindrome (61322316).

The spelling of 21002304 in words is "twenty-one million, two thousand, three hundred four".