31561672320 has 384 divisors, whose sum is σ = 116188946640. Its totient is φ = 7867072512.

The previous prime is 31561672313. The next prime is 31561672339. The reversal of 31561672320 is 2327616513.

31561672320 is a `hidden beast` number, since 3 + 1 + 5 + 616 + 7 + 2 + 32 + 0 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 15093596736 + 16468075584 = 122856^2 + 128328^2 .

It is a tau number, because it is divible by the number of its divisors (384).

It is a super-2 number, since 2×31561672320² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 15372414 + ... + 15374466.

Almost surely, 2^31561672320 is an apocalyptic number.

31561672320 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 31561672320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (58094473320).

31561672320 is an abundant number, since it is smaller than the sum of its proper divisors (84627274320).

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

31561672320 is a wasteful number, since it uses less digits than its factorization.

31561672320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2252 (or 2237 counting only the distinct ones).

The product of its (nonzero) digits is 45360, while the sum is 36.

The spelling of 31561672320 in words is "thirty-one billion, five hundred sixty-one million, six hundred seventy-two thousand, three hundred twenty".