21312110231 has 4 divisors (see below), whose sum is σ = 22565763792. Its totient is φ = 20058456672.

The previous prime is 21312110227. The next prime is 21312110251. The reversal of 21312110231 is 13201121312.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21312110231 - 2² = 21312110227 is a prime.

It is a super-2 number, since 2×21312110231² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 1253653543 = 21312110231 / (2 + 1 + 3 + 1 + 2 + 1 + 1 + 0 + 2 + 3 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21312110251) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 626826755 + ... + 626826788.

It is an arithmetic number, because the mean of its divisors is an integer number (5641440948).

Almost surely, 2^21312110231 is an apocalyptic number.

21312110231 is a deficient number, since it is larger than the sum of its proper divisors (1253653561).

21312110231 is a wasteful number, since it uses less digits than its factorization.

21312110231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1253653560.

The product of its (nonzero) digits is 72, while the sum is 17.

Adding to 21312110231 its reverse (13201121312), we get a palindrome (34513231543).

The spelling of 21312110231 in words is "twenty-one billion, three hundred twelve million, one hundred ten thousand, two hundred thirty-one".