640643344 has 20 divisors (see below), whose sum is σ = 1354087440. Its totient is φ = 291201440.

The previous prime is 640643329. The next prime is 640643363. The reversal of 640643344 is 443346046.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1819834 + ... + 1820185.

It is an arithmetic number, because the mean of its divisors is an integer number (67704372).

Almost surely, 2^640643344 is an apocalyptic number.

It is an amenable number.

640643344 is an abundant number, since it is smaller than the sum of its proper divisors (713444096).

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

640643344 is a wasteful number, since it uses less digits than its factorization.

640643344 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3640038 (or 3640032 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 34.

The square root of 640643344 is about 25310.9332897861. The cubic root of 640643344 is about 862.0625381924.

The spelling of 640643344 in words is "six hundred forty million, six hundred forty-three thousand, three hundred forty-four".