21312123200 has 84 divisors (see below), whose sum is σ = 54249576540. Its totient is φ = 8230871040.

The previous prime is 21312123187. The next prime is 21312123211. The reversal of 21312123200 is 232121312.

It can be written as a sum of positive squares in 6 ways, for example, as 1381460224 + 19930662976 = 37168^2 + 141176^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 183257 + ... + 276056.

Almost surely, 2^21312123200 is an apocalyptic number.

21312123200 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21312123200 is an abundant number, since it is smaller than the sum of its proper divisors (32937453340).

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

21312123200 is a wasteful number, since it uses less digits than its factorization.

21312123200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 459364 (or 459349 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 17.

Adding to 21312123200 its reverse (232121312), we get a palindrome (21544244512).

The spelling of 21312123200 in words is "twenty-one billion, three hundred twelve million, one hundred twenty-three thousand, two hundred".