640346668 has 24 divisors (see below), whose sum is σ = 1210693568. Its totient is φ = 294592896.

The previous prime is 640346627. The next prime is 640346711. The reversal of 640346668 is 866643046.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3396 + ... + 35947.

Almost surely, 2^640346668 is an apocalyptic number.

It is an amenable number.

640346668 is a deficient number, since it is larger than the sum of its proper divisors (570346900).

640346668 is a wasteful number, since it uses less digits than its factorization.

640346668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39673 (or 39671 counting only the distinct ones).

The product of its (nonzero) digits is 497664, while the sum is 43.

The square root of 640346668 is about 25305.0719817194. The cubic root of 640346668 is about 861.9294465863.

The spelling of 640346668 in words is "six hundred forty million, three hundred forty-six thousand, six hundred sixty-eight".