31991317560 has 96 divisors (see below), whose sum is σ = 104142111840. Its totient is φ = 8517042432.

The previous prime is 31991317559. The next prime is 31991317627. The reversal of 31991317560 is 6571319913.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 148197 + ... + 293163.

It is an arithmetic number, because the mean of its divisors is an integer number (1084813665).

Almost surely, 2^31991317560 is an apocalyptic number.

31991317560 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31991317560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (52071055920).

31991317560 is an abundant number, since it is smaller than the sum of its proper divisors (72150794280).

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

31991317560 is a wasteful number, since it uses less digits than its factorization.

31991317560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145597 (or 145590 counting only the distinct ones).

The product of its (nonzero) digits is 153090, while the sum is 45.

The spelling of 31991317560 in words is "thirty-one billion, nine hundred ninety-one million, three hundred seventeen thousand, five hundred sixty".