640904444 has 6 divisors (see below), whose sum is σ = 1121582784. Its totient is φ = 320452220.

The previous prime is 640904443. The next prime is 640904483. The reversal of 640904444 is 444409046.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640904443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80113052 + ... + 80113059.

It is an arithmetic number, because the mean of its divisors is an integer number (186930464).

Almost surely, 2^640904444 is an apocalyptic number.

It is an amenable number.

640904444 is a deficient number, since it is larger than the sum of its proper divisors (480678340).

640904444 is a wasteful number, since it uses less digits than its factorization.

640904444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160226115 (or 160226113 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 35.

The square root of 640904444 is about 25316.0906144689. The cubic root of 640904444 is about 862.1796360854.

The spelling of 640904444 in words is "six hundred forty million, nine hundred four thousand, four hundred forty-four".