31981481751 has 4 divisors (see below), whose sum is σ = 42641975672. Its totient is φ = 21320987832.

The previous prime is 31981481743. The next prime is 31981481789. The reversal of 31981481751 is 15718418913.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15718418913 = 3 ⋅5239472971.

It is not a de Polignac number, because 31981481751 - 2³ = 31981481743 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 31981481751.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31981482751) 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, 5330246956 + ... + 5330246961.

It is an arithmetic number, because the mean of its divisors is an integer number (10660493918).

Almost surely, 2^31981481751 is an apocalyptic number.

31981481751 is a deficient number, since it is larger than the sum of its proper divisors (10660493921).

31981481751 is a wasteful number, since it uses less digits than its factorization.

31981481751 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10660493920.

The product of its digits is 241920, while the sum is 48.

The spelling of 31981481751 in words is "thirty-one billion, nine hundred eighty-one million, four hundred eighty-one thousand, seven hundred fifty-one".