640640886 has 32 divisors (see below), whose sum is σ = 1369353600. Its totient is φ = 199103616.

The previous prime is 640640863. The next prime is 640640893. The reversal of 640640886 is 688046046.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18436 + ... + 40263.

It is an arithmetic number, because the mean of its divisors is an integer number (42792300).

Almost surely, 2^640640886 is an apocalyptic number.

640640886 is an abundant number, since it is smaller than the sum of its proper divisors (728712714).

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

640640886 is a wasteful number, since it uses less digits than its factorization.

640640886 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58828.

The product of its (nonzero) digits is 221184, while the sum is 42.

The square root of 640640886 is about 25310.8847336477. The cubic root of 640640886 is about 862.0614356796.

The spelling of 640640886 in words is "six hundred forty million, six hundred forty thousand, eight hundred eighty-six".