644896252 has 192 divisors, whose sum is σ = 1636992000. Its totient is φ = 218453760.

The previous prime is 644896243. The next prime is 644896253. The reversal of 644896252 is 252698446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644896253) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3727638 + ... + 3727810.

It is an arithmetic number, because the mean of its divisors is an integer number (8526000).

Almost surely, 2^644896252 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 644896252, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (818496000).

644896252 is an abundant number, since it is smaller than the sum of its proper divisors (992095748).

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

644896252 is a wasteful number, since it uses less digits than its factorization.

644896252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 241 (or 225 counting only the distinct ones).

The product of its digits is 829440, while the sum is 46.

The square root of 644896252 is about 25394.8075795033. The cubic root of 644896252 is about 863.9659319414.

The spelling of 644896252 in words is "six hundred forty-four million, eight hundred ninety-six thousand, two hundred fifty-two".