640493818 has 8 divisors (see below), whose sum is σ = 960925248. Its totient is φ = 320185404.

The previous prime is 640493773. The next prime is 640493827. The reversal of 640493818 is 818394046.

640493818 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

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, 16396 + ... + 39367.

It is an arithmetic number, because the mean of its divisors is an integer number (120115656).

Almost surely, 2^640493818 is an apocalyptic number.

640493818 is a deficient number, since it is larger than the sum of its proper divisors (320431430).

640493818 is a wasteful number, since it uses less digits than its factorization.

640493818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61508.

The product of its (nonzero) digits is 165888, while the sum is 43.

The square root of 640493818 is about 25307.9793345893. The cubic root of 640493818 is about 861.9954645785.

The spelling of 640493818 in words is "six hundred forty million, four hundred ninety-three thousand, eight hundred eighteen".