640208994 has 16 divisors (see below), whose sum is σ = 1283855232. Its totient is φ = 212830128.

The previous prime is 640208957. The next prime is 640209023. The reversal of 640208994 is 499802046.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 140794 + ... + 145269.

It is an arithmetic number, because the mean of its divisors is an integer number (80240952).

Almost surely, 2^640208994 is an apocalyptic number.

640208994 is an abundant number, since it is smaller than the sum of its proper divisors (643646238).

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

640208994 is a wasteful number, since it uses less digits than its factorization.

640208994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 286441.

The product of its (nonzero) digits is 124416, while the sum is 42.

The square root of 640208994 is about 25302.3515507946. The cubic root of 640208994 is about 861.8676707879.

The spelling of 640208994 in words is "six hundred forty million, two hundred eight thousand, nine hundred ninety-four".