21312031200 has 144 divisors (see below), whose sum is σ = 69678040320. Its totient is φ = 5658027520.

The previous prime is 21312031171. The next prime is 21312031201. The reversal of 21312031200 is 213021312.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21312031200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21312031201) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 525241 + ... + 564359.

It is an arithmetic number, because the mean of its divisors is an integer number (483875280).

Almost surely, 2^21312031200 is an apocalyptic number.

21312031200 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 21312031200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34839020160).

21312031200 is an abundant number, since it is smaller than the sum of its proper divisors (48366009120).

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

21312031200 is a wasteful number, since it uses less digits than its factorization.

21312031200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39369 (or 39356 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 15.

Adding to 21312031200 its reverse (213021312), we get a palindrome (21525052512).

The spelling of 21312031200 in words is "twenty-one billion, three hundred twelve million, thirty-one thousand, two hundred".