644252 has 36 divisors (see below), whose sum is σ = 1388520. Its totient is φ = 260064.

The previous prime is 644239. The next prime is 644257. The reversal of 644252 is 252446.

644252 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an Ulam number.

It is a nialpdrome in base 7.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 644252.

It is not an unprimeable number, because it can be changed into a prime (644257) by changing a digit.

644252 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3638 + ... + 3810.

It is an arithmetic number, because the mean of its divisors is an integer number (38570).

2⁶⁴⁴²⁵² 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 644252, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (694260).

644252 is an abundant number, since it is smaller than the sum of its proper divisors (744268).

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

644252 is a wasteful number, since it uses less digits than its factorization.

644252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210 (or 201 counting only the distinct ones).

The product of its digits is 1920, while the sum is 23.

The square root of 644252 is about 802.6531006606. The cubic root of 644252 is about 86.3678135141.

Adding to 644252 its reverse (252446), we get a palindrome (896698).

The spelling of 644252 in words is "six hundred forty-four thousand, two hundred fifty-two".