644886752 has 48 divisors (see below), whose sum is σ = 1355356800. Its totient is φ = 301150080.

The previous prime is 644886703. The next prime is 644886757. The reversal of 644886752 is 257688446.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 644886752.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644886757) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35699 + ... + 50637.

It is an arithmetic number, because the mean of its divisors is an integer number (28236600).

Almost surely, 2^644886752 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 644886752, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (677678400).

644886752 is an abundant number, since it is smaller than the sum of its proper divisors (710470048).

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

644886752 is a wasteful number, since it uses less digits than its factorization.

644886752 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15039 (or 15031 counting only the distinct ones).

The product of its digits is 2580480, while the sum is 50.

The square root of 644886752 is about 25394.6205327034. The cubic root of 644886752 is about 863.9616895450.

The spelling of 644886752 in words is "six hundred forty-four million, eight hundred eighty-six thousand, seven hundred fifty-two".