640348906 has 16 divisors (see below), whose sum is σ = 1035740160. Its totient is φ = 295924320.

The previous prime is 640348897. The next prime is 640348921. The reversal of 640348906 is 609843046.

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, 203946 + ... + 207061.

It is an arithmetic number, because the mean of its divisors is an integer number (64733760).

Almost surely, 2^640348906 is an apocalyptic number.

640348906 is a deficient number, since it is larger than the sum of its proper divisors (395391254).

640348906 is a wasteful number, since it uses less digits than its factorization.

640348906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 411069.

The product of its (nonzero) digits is 124416, while the sum is 40.

The square root of 640348906 is about 25305.1162020648. The cubic root of 640348906 is about 861.9304507277.

The spelling of 640348906 in words is "six hundred forty million, three hundred forty-eight thousand, nine hundred six".