640709633944 has 8 divisors (see below), whose sum is σ = 1201330563660. Its totient is φ = 320354816968.

The previous prime is 640709633911. The next prime is 640709633951. The reversal of 640709633944 is 449336907046.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40044352114 + ... + 40044352129.

Almost surely, 2^640709633944 is an apocalyptic number.

It is an amenable number.

640709633944 is a deficient number, since it is larger than the sum of its proper divisors (560620929716).

640709633944 is a wasteful number, since it uses less digits than its factorization.

640709633944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80088704249 (or 80088704245 counting only the distinct ones).

The product of its (nonzero) digits is 11757312, while the sum is 55.

The spelling of 640709633944 in words is "six hundred forty billion, seven hundred nine million, six hundred thirty-three thousand, nine hundred forty-four".