640666602 has 12 divisors (see below), whose sum is σ = 1388111010. Its totient is φ = 213555528.

The previous prime is 640666561. The next prime is 640666619. The reversal of 640666602 is 206666046.

It can be written as a sum of positive squares in only one way, i.e., 640646721 + 19881 = 25311^2 + 141^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17796277 + ... + 17796312.

Almost surely, 2^640666602 is an apocalyptic number.

640666602 is an abundant number, since it is smaller than the sum of its proper divisors (747444408).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640666602 is a wasteful number, since it uses less digits than its factorization.

640666602 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35592597 (or 35592594 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 36.

The square root of 640666602 is about 25311.3927313374. The cubic root of 640666602 is about 862.0729702100.

The spelling of 640666602 in words is "six hundred forty million, six hundred sixty-six thousand, six hundred two".