21304520 has 32 divisors (see below), whose sum is σ = 48409920. Its totient is φ = 8437440.

The previous prime is 21304511. The next prime is 21304537. The reversal of 21304520 is 2540312.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1535 + ... + 6705.

It is an arithmetic number, because the mean of its divisors is an integer number (1512810).

Almost surely, 2^21304520 is an apocalyptic number.

21304520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21304520 is an abundant number, since it is smaller than the sum of its proper divisors (27105400).

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

21304520 is a wasteful number, since it uses less digits than its factorization.

21304520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5285 (or 5281 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 21304520 is about 4615.6819647805. The cubic root of 21304520 is about 277.2195906743.

Adding to 21304520 its reverse (2540312), we get a palindrome (23844832).

The spelling of 21304520 in words is "twenty-one million, three hundred four thousand, five hundred twenty".