21312400 has 30 divisors (see below), whose sum is σ = 51204002. Its totient is φ = 8524800.

The previous prime is 21312341. The next prime is 21312427. The reversal of 21312400 is 421312.

It can be written as a sum of positive squares in 3 ways, for example, as 1527696 + 19784704 = 1236^2 + 4448^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 26241 + ... + 27040.

Almost surely, 2^21312400 is an apocalyptic number.

21312400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21312400 is an abundant number, since it is smaller than the sum of its proper divisors (29891602).

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

21312400 is a wasteful number, since it uses less digits than its factorization.

21312400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53299 (or 53288 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21312400 is about 4616.5354975349. The cubic root of 21312400 is about 277.2537652861.

Adding to 21312400 its reverse (421312), we get a palindrome (21733712).

It can be divided in two parts, 21312 and 400, that added together give a palindrome (21712).

The spelling of 21312400 in words is "twenty-one million, three hundred twelve thousand, four hundred".