31213313231 has 4 divisors (see below), whose sum is σ = 31216057152. Its totient is φ = 31210569312.

The previous prime is 31213313203. The next prime is 31213313251. The reversal of 31213313231 is 13231331213.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31213313231 is a prime.

It is a super-2 number, since 2×31213313231² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31213313197 and 31213313206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31213313251) 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, 1354826 + ... + 1377671.

It is an arithmetic number, because the mean of its divisors is an integer number (7804014288).

Almost surely, 2^31213313231 is an apocalyptic number.

31213313231 is a deficient number, since it is larger than the sum of its proper divisors (2743921).

31213313231 is a wasteful number, since it uses less digits than its factorization.

31213313231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2743920.

The product of its digits is 972, while the sum is 23.

Adding to 31213313231 its reverse (13231331213), we get a palindrome (44444644444).

The spelling of 31213313231 in words is "thirty-one billion, two hundred thirteen million, three hundred thirteen thousand, two hundred thirty-one".