31978397617920 has 1080 divisors, whose sum is σ = 124157489890896. Its totient is φ = 7855478931456.

The previous prime is 31978397617877. The next prime is 31978397617939. The reversal of 31978397617920 is 2971679387913.

31978397617920 is a `hidden beast` number, since 3 + 1 + 97 + 8 + 397 + 61 + 7 + 92 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1080).

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 10110146259 + ... + 10110149421.

Almost surely, 2^{31978397617920} is an apocalyptic number.

31978397617920 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 31978397617920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (62078744945448).

31978397617920 is an abundant number, since it is smaller than the sum of its proper divisors (92179092272976).

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

31978397617920 is a wasteful number, since it uses less digits than its factorization.

31978397617920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3799 (or 3763 counting only the distinct ones).

The product of its (nonzero) digits is 216040608, while the sum is 72.

The spelling of 31978397617920 in words is "thirty-one trillion, nine hundred seventy-eight billion, three hundred ninety-seven million, six hundred seventeen thousand, nine hundred twenty".