644857572 has 48 divisors (see below), whose sum is σ = 1585967040. Its totient is φ = 203618688.

The previous prime is 644857523. The next prime is 644857579. The reversal of 644857572 is 275758446.

It is not an unprimeable number, because it can be changed into a prime (644857579) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 963 + ... + 35925.

It is an arithmetic number, because the mean of its divisors is an integer number (33040980).

Almost surely, 2^644857572 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 644857572, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (792983520).

644857572 is an abundant number, since it is smaller than the sum of its proper divisors (941109468).

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

644857572 is a wasteful number, since it uses less digits than its factorization.

644857572 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35052 (or 35050 counting only the distinct ones).

The product of its digits is 1881600, while the sum is 48.

The square root of 644857572 is about 25394.0459950753. The cubic root of 644857572 is about 863.9486584290.

The spelling of 644857572 in words is "six hundred forty-four million, eight hundred fifty-seven thousand, five hundred seventy-two".