640815957 has 12 divisors (see below), whose sum is σ = 926250624. Its totient is φ = 426921000.

The previous prime is 640815899. The next prime is 640815961. The reversal of 640815957 is 759518046.

It is not a de Polignac number, because 640815957 - 2⁷ = 640815829 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640815977) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9669 + ... + 37082.

It is an arithmetic number, because the mean of its divisors is an integer number (77187552).

Almost surely, 2^640815957 is an apocalyptic number.

It is an amenable number.

640815957 is a deficient number, since it is larger than the sum of its proper divisors (285434667).

640815957 is a wasteful number, since it uses less digits than its factorization.

640815957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48280 (or 48277 counting only the distinct ones).

The product of its (nonzero) digits is 302400, while the sum is 45.

The square root of 640815957 is about 25314.3429106900. The cubic root of 640815957 is about 862.1399550786.

The spelling of 640815957 in words is "six hundred forty million, eight hundred fifteen thousand, nine hundred fifty-seven".