640635976 has 16 divisors (see below), whose sum is σ = 1201486140. Its totient is φ = 320239680.

The previous prime is 640635967. The next prime is 640636021. The reversal of 640635976 is 679536046.

It can be written as a sum of positive squares in 2 ways, for example, as 636351076 + 4284900 = 25226^2 + 2070^2 .

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 39690 + ... + 53446.

Almost surely, 2^640635976 is an apocalyptic number.

It is an amenable number.

640635976 is a deficient number, since it is larger than the sum of its proper divisors (560850164).

640635976 is a wasteful number, since it uses less digits than its factorization.

640635976 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19584 (or 19580 counting only the distinct ones).

The product of its (nonzero) digits is 816480, while the sum is 46.

The square root of 640635976 is about 25310.7877396181. The cubic root of 640635976 is about 862.0592333368.

The spelling of 640635976 in words is "six hundred forty million, six hundred thirty-five thousand, nine hundred seventy-six".