644366268 has 108 divisors (see below), whose sum is σ = 2040565800. Its totient is φ = 169936704.

The previous prime is 644366257. The next prime is 644366297. The reversal of 644366268 is 862663446.

It is a congruent number.

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 35 ways as a sum of consecutive naturals, for example, 8883 + ... + 36981.

Almost surely, 2^644366268 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 644366268, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1020282900).

644366268 is an abundant number, since it is smaller than the sum of its proper divisors (1396199532).

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

644366268 is a wasteful number, since it uses less digits than its factorization.

644366268 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28136 (or 28124 counting only the distinct ones).

The product of its digits is 995328, while the sum is 45.

The square root of 644366268 is about 25384.3705456724. The cubic root of 644366268 is about 863.7291943220.

The spelling of 644366268 in words is "six hundred forty-four million, three hundred sixty-six thousand, two hundred sixty-eight".