640461907 has 4 divisors (see below), whose sum is σ = 646803216. Its totient is φ = 634120600.

The previous prime is 640461901. The next prime is 640461919. The reversal of 640461907 is 709164046.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640461907 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640461901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3170503 + ... + 3170704.

It is an arithmetic number, because the mean of its divisors is an integer number (161700804).

Almost surely, 2^640461907 is an apocalyptic number.

640461907 is a deficient number, since it is larger than the sum of its proper divisors (6341309).

640461907 is a wasteful number, since it uses less digits than its factorization.

640461907 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6341308.

The product of its (nonzero) digits is 36288, while the sum is 37.

The square root of 640461907 is about 25307.3488734004. The cubic root of 640461907 is about 861.9811487525.

The spelling of 640461907 in words is "six hundred forty million, four hundred sixty-one thousand, nine hundred seven".