21031231312 has 40 divisors (see below), whose sum is σ = 50151401216. Its totient is φ = 8320046976.

The previous prime is 21031231297. The next prime is 21031231343. The reversal of 21031231312 is 21313213012.

It is a self number, because there is not a number n which added to its sum of digits gives 21031231312.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7220808 + ... + 7223719.

Almost surely, 2^21031231312 is an apocalyptic number.

It is an amenable number.

21031231312 is an abundant number, since it is smaller than the sum of its proper divisors (29120169904).

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

21031231312 is a wasteful number, since it uses less digits than its factorization.

21031231312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14444555 (or 14444549 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 19.

Adding to 21031231312 its reverse (21313213012), we get a palindrome (42344444324).

The spelling of 21031231312 in words is "twenty-one billion, thirty-one million, two hundred thirty-one thousand, three hundred twelve".