644334253 has 2 divisors, whose sum is σ = 644334254. Its totient is φ = 644334252.

The previous prime is 644334217. The next prime is 644334331. The reversal of 644334253 is 352433446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 405539044 + 238795209 = 20138^2 + 15453^2 .

It is a cyclic number.

It is not a de Polignac number, because 644334253 - 2²⁵ = 610779821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644334953) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322167126 + 322167127.

It is an arithmetic number, because the mean of its divisors is an integer number (322167127).

Almost surely, 2^644334253 is an apocalyptic number.

It is an amenable number.

644334253 is a deficient number, since it is larger than the sum of its proper divisors (1).

644334253 is an equidigital number, since it uses as much as digits as its factorization.

644334253 is an evil number, because the sum of its binary digits is even.

The product of its digits is 103680, while the sum is 34.

The square root of 644334253 is about 25383.7399332722. The cubic root of 644334253 is about 863.7148894411.

Adding to 644334253 its reverse (352433446), we get a palindrome (996767699).

It can be divided in two parts, 64433 and 4253, that added together give a palindrome (68686).

The spelling of 644334253 in words is "six hundred forty-four million, three hundred thirty-four thousand, two hundred fifty-three".