31121311213 has 4 divisors (see below), whose sum is σ = 31123998108. Its totient is φ = 31118624320.

The previous prime is 31121311183. The next prime is 31121311237. The reversal of 31121311213 is 31211312113.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31211312113 = 379 ⋅82351747.

It can be written as a sum of positive squares in 2 ways, for example, as 7871770729 + 23249540484 = 88723^2 + 152478^2 .

It is a cyclic number.

It is not a de Polignac number, because 31121311213 - 2¹³ = 31121303021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31121311513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1325998 + ... + 1349263.

It is an arithmetic number, because the mean of its divisors is an integer number (7780999527).

Almost surely, 2^31121311213 is an apocalyptic number.

It is an amenable number.

31121311213 is a deficient number, since it is larger than the sum of its proper divisors (2686895).

31121311213 is a wasteful number, since it uses less digits than its factorization.

31121311213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2686894.

The product of its digits is 108, while the sum is 19.

Adding to 31121311213 its reverse (31211312113), we get a palindrome (62332623326).

The spelling of 31121311213 in words is "thirty-one billion, one hundred twenty-one million, three hundred eleven thousand, two hundred thirteen".