31881318813 has 12 divisors (see below), whose sum is σ = 46081290528. Its totient is φ = 21240137160.

The previous prime is 31881318803. The next prime is 31881318893.

31881318813 is a `hidden beast` number, since 318 + 8 + 1 + 318 + 8 + 13 = 666.

31881318813 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 31881318813 - 2³⁴ = 14701449629 is a prime.

It is a super-2 number, since 2×31881318813² (a number of 22 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31881318803) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1158595 + ... + 1185792.

It is an arithmetic number, because the mean of its divisors is an integer number (3840107544).

Almost surely, 2^31881318813 is an apocalyptic number.

It is an amenable number.

31881318813 is a deficient number, since it is larger than the sum of its proper divisors (14199971715).

31881318813 is a wasteful number, since it uses less digits than its factorization.

31881318813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2345904 (or 2345901 counting only the distinct ones).

The product of its digits is 110592, while the sum is 45.

It can be divided in two parts, 3188131 and 8813, that added together give a square (3196944 = 1788²).

The spelling of 31881318813 in words is "thirty-one billion, eight hundred eighty-one million, three hundred eighteen thousand, eight hundred thirteen".