640634644 has 24 divisors (see below), whose sum is σ = 1208216520. Its totient is φ = 295465344.

The previous prime is 640634639. The next prime is 640634677. The reversal of 640634644 is 446436046.

640634644 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 544644 + 640090000 = 738^2 + 25300^2 .

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 86562 + ... + 93670.

It is an arithmetic number, because the mean of its divisors is an integer number (50342355).

Almost surely, 2^640634644 is an apocalyptic number.

It is an amenable number.

640634644 is a deficient number, since it is larger than the sum of its proper divisors (567581876).

640634644 is a wasteful number, since it uses less digits than its factorization.

640634644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8859 (or 8857 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 37.

The square root of 640634644 is about 25310.7614267133. The cubic root of 640634644 is about 862.0586358765.

It can be divided in two parts, 640634 and 644, that added together give a triangular number (641278 = T₁₁₃₂).

The spelling of 640634644 in words is "six hundred forty million, six hundred thirty-four thousand, six hundred forty-four".