31131817938 has 128 divisors (see below), whose sum is σ = 76733395200. Its totient is φ = 9295243776.

The previous prime is 31131817903. The next prime is 31131817949. The reversal of 31131817938 is 83971813113.

31131817938 is a `hidden beast` number, since 311 + 318 + 17 + 9 + 3 + 8 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 31131817893 and 31131817902.

It is an unprimeable number.

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 63 ways as a sum of consecutive naturals, for example, 4735918 + ... + 4742486.

It is an arithmetic number, because the mean of its divisors is an integer number (599479650).

Almost surely, 2^31131817938 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31131817938, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38366697600).

31131817938 is an abundant number, since it is smaller than the sum of its proper divisors (45601577262).

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

31131817938 is a wasteful number, since it uses less digits than its factorization.

31131817938 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6793 (or 6787 counting only the distinct ones).

The product of its digits is 108864, while the sum is 45.

The spelling of 31131817938 in words is "thirty-one billion, one hundred thirty-one million, eight hundred seventeen thousand, nine hundred thirty-eight".