640131515631 has 48 divisors (see below), whose sum is σ = 984966796320. Its totient is φ = 410866283520.

The previous prime is 640131515627. The next prime is 640131515669. The reversal of 640131515631 is 136515131046.

640131515631 is a `hidden beast` number, since 6 + 4 + 0 + 1 + 3 + 1 + 5 + 15 + 631 = 666.

It is not a de Polignac number, because 640131515631 - 2² = 640131515627 is a prime.

It is a super-2 number, since 2×640131515631² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640131515671) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 7975641 + ... + 8055501.

It is an arithmetic number, because the mean of its divisors is an integer number (20520141590).

Almost surely, 2^640131515631 is an apocalyptic number.

640131515631 is a deficient number, since it is larger than the sum of its proper divisors (344835280689).

640131515631 is a wasteful number, since it uses less digits than its factorization.

640131515631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80281 (or 80246 counting only the distinct ones).

The product of its (nonzero) digits is 32400, while the sum is 36.

Adding to 640131515631 its reverse (136515131046), we get a palindrome (776646646677).

The spelling of 640131515631 in words is "six hundred forty billion, one hundred thirty-one million, five hundred fifteen thousand, six hundred thirty-one".