21312230400 has 396 divisors, whose sum is σ = 76828405212. Its totient is φ = 5644615680.

The previous prime is 21312230351. The next prime is 21312230411. The reversal of 21312230400 is 403221312.

21312230400 is a `hidden beast` number, since 2 + 1 + 31 + 2 + 230 + 400 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 961496064 + 20350734336 = 31008^2 + 142656^2 .

It is a super-2 number, since 2×21312230400² (a number of 21 digits) contains 22 as substring.

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 polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 53683002 + ... + 53683398.

Almost surely, 2^21312230400 is an apocalyptic number.

21312230400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21312230400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38414202606).

21312230400 is an abundant number, since it is smaller than the sum of its proper divisors (55516174812).

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

21312230400 is a wasteful number, since it uses less digits than its factorization.

21312230400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 666 (or 640 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

Adding to 21312230400 its reverse (403221312), we get a palindrome (21715451712).

The spelling of 21312230400 in words is "twenty-one billion, three hundred twelve million, two hundred thirty thousand, four hundred".