640985696 has 24 divisors (see below), whose sum is σ = 1359013824. Its totient is φ = 295839360.

The previous prime is 640985659. The next prime is 640985701. The reversal of 640985696 is 696589046.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 770000 + ... + 770831.

It is an arithmetic number, because the mean of its divisors is an integer number (56625576).

Almost surely, 2^640985696 is an apocalyptic number.

It is an amenable number.

640985696 is an abundant number, since it is smaller than the sum of its proper divisors (718028128).

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

640985696 is a wasteful number, since it uses less digits than its factorization.

640985696 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1540854 (or 1540846 counting only the distinct ones).

The product of its (nonzero) digits is 2799360, while the sum is 53.

The square root of 640985696 is about 25317.6953137524. The cubic root of 640985696 is about 862.2160694207.

The spelling of 640985696 in words is "six hundred forty million, nine hundred eighty-five thousand, six hundred ninety-six".