640631415631 has 2 divisors, whose sum is σ = 640631415632. Its totient is φ = 640631415630.

The previous prime is 640631415617. The next prime is 640631415701. The reversal of 640631415631 is 136514136046.

640631415631 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640631415631 is a prime.

It is a super-2 number, since 2×640631415631² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640631515631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320315707815 + 320315707816.

It is an arithmetic number, because the mean of its divisors is an integer number (320315707816).

Almost surely, 2^640631415631 is an apocalyptic number.

640631415631 is a deficient number, since it is larger than the sum of its proper divisors (1).

640631415631 is an equidigital number, since it uses as much as digits as its factorization.

640631415631 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 155520, while the sum is 40.

The spelling of 640631415631 in words is "six hundred forty billion, six hundred thirty-one million, four hundred fifteen thousand, six hundred thirty-one".