644253 has 8 divisors (see below), whose sum is σ = 896448. Its totient is φ = 410784.

The previous prime is 644239. The next prime is 644257. The reversal of 644253 is 352446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 644253 - 2¹³ = 636061 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644257) 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, 4600 + ... + 4737.

It is an arithmetic number, because the mean of its divisors is an integer number (112056).

2⁶⁴⁴²⁵³ is an apocalyptic number.

It is an amenable number.

644253 is a deficient number, since it is larger than the sum of its proper divisors (252195).

644253 is a wasteful number, since it uses less digits than its factorization.

644253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9363.

The product of its digits is 2880, while the sum is 24.

The square root of 644253 is about 802.6537235944. The cubic root of 644253 is about 86.3678582004.

Adding to 644253 its reverse (352446), we get a palindrome (996699).

The spelling of 644253 in words is "six hundred forty-four thousand, two hundred fifty-three".