21312504 has 32 divisors (see below), whose sum is σ = 59202000. Its totient is φ = 7104096.

The previous prime is 21312493. The next prime is 21312517. The reversal of 21312504 is 40521312.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49119 + ... + 49550.

Almost surely, 2^21312504 is an apocalyptic number.

21312504 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21312504 is an abundant number, since it is smaller than the sum of its proper divisors (37889496).

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

21312504 is a wasteful number, since it uses less digits than its factorization.

21312504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98684 (or 98674 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21312504 is about 4616.5467613791. The cubic root of 21312504 is about 277.2542162652.

Adding to 21312504 its reverse (40521312), we get a palindrome (61833816).

The spelling of 21312504 in words is "twenty-one million, three hundred twelve thousand, five hundred four".