644059968 has 112 divisors (see below), whose sum is σ = 1770278400. Its totient is φ = 206438400.

The previous prime is 644059919. The next prime is 644059991. The reversal of 644059968 is 869950446.

644059968 is nontrivially palindromic in base 15.

It is a super-2 number, since 2×644059968² = 829626484760322048, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 644059968.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1434208 + ... + 1434656.

Almost surely, 2^644059968 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 644059968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (885139200).

644059968 is an abundant number, since it is smaller than the sum of its proper divisors (1126218432).

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

644059968 is a wasteful number, since it uses less digits than its factorization.

644059968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 736 (or 726 counting only the distinct ones).

The product of its (nonzero) digits is 1866240, while the sum is 51.

The square root of 644059968 is about 25378.3365885158. The cubic root of 644059968 is about 863.5923145192.

The spelling of 644059968 in words is "six hundred forty-four million, fifty-nine thousand, nine hundred sixty-eight".