644660044464 has 40 divisors (see below), whose sum is σ = 1665678759280. Its totient is φ = 214847071488.

The previous prime is 644660044463. The next prime is 644660044477. The reversal of 644660044464 is 464440066446.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is not an unprimeable number, because it can be changed into a prime (644660044463) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 974119 + ... + 1496070.

It is an arithmetic number, because the mean of its divisors is an integer number (41641968982).

Almost surely, 2^644660044464 is an apocalyptic number.

It is an amenable number.

644660044464 is an abundant number, since it is smaller than the sum of its proper divisors (1021018714816).

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

644660044464 is a wasteful number, since it uses less digits than its factorization.

644660044464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2475637 (or 2475631 counting only the distinct ones).

The product of its (nonzero) digits is 5308416, while the sum is 48.

The spelling of 644660044464 in words is "six hundred forty-four billion, six hundred sixty million, forty-four thousand, four hundred sixty-four".