640808912 has 20 divisors (see below), whose sum is σ = 1262612640. Its totient is φ = 314973408.

The previous prime is 640808881. The next prime is 640808923. The reversal of 640808912 is 219808046.

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, 338468 + ... + 340355.

It is an arithmetic number, because the mean of its divisors is an integer number (63130632).

Almost surely, 2^640808912 is an apocalyptic number.

It is an amenable number.

640808912 is a deficient number, since it is larger than the sum of its proper divisors (621803728).

640808912 is a wasteful number, since it uses less digits than its factorization.

640808912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 678890 (or 678884 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 38.

The square root of 640808912 is about 25314.2037599447. The cubic root of 640808912 is about 862.1367956700.

The spelling of 640808912 in words is "six hundred forty million, eight hundred eight thousand, nine hundred twelve".