644044312464 has 160 divisors (see below), whose sum is σ = 1936166077440. Its totient is φ = 180662401536.

The previous prime is 644044312451. The next prime is 644044312489. The reversal of 644044312464 is 464213440446.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is an unprimeable number.

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 in 31 ways as a sum of consecutive naturals, for example, 15779347 + ... + 15820109.

It is an arithmetic number, because the mean of its divisors is an integer number (12101037984).

Almost surely, 2^644044312464 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644044312464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (968083038720).

644044312464 is an abundant number, since it is smaller than the sum of its proper divisors (1292121764976).

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

644044312464 is a wasteful number, since it uses less digits than its factorization.

644044312464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41637 (or 41631 counting only the distinct ones).

The product of its (nonzero) digits is 884736, while the sum is 42.

The spelling of 644044312464 in words is "six hundred forty-four billion, forty-four million, three hundred twelve thousand, four hundred sixty-four".