31215790640 has 20 divisors (see below), whose sum is σ = 72576713424. Its totient is φ = 12486316224.

The previous prime is 31215790637. The next prime is 31215790649. The reversal of 31215790640 is 4609751213.

It is a tau number, because it is divible by the number of its divisors (20).

It is a junction number, because it is equal to n+sod(n) for n = 31215790594 and 31215790603.

It is not an unprimeable number, because it can be changed into a prime (31215790649) 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, 195098612 + ... + 195098771.

Almost surely, 2^31215790640 is an apocalyptic number.

It is an amenable number.

31215790640 is an abundant number, since it is smaller than the sum of its proper divisors (41360922784).

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

31215790640 is a wasteful number, since it uses less digits than its factorization.

31215790640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 390197396 (or 390197390 counting only the distinct ones).

The product of its (nonzero) digits is 45360, while the sum is 38.

The spelling of 31215790640 in words is "thirty-one billion, two hundred fifteen million, seven hundred ninety thousand, six hundred forty".