644104253 has 4 divisors (see below), whose sum is σ = 693650748. Its totient is φ = 594557760.

The previous prime is 644104207. The next prime is 644104291. The reversal of 644104253 is 352401446.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 373764889 + 270339364 = 19333^2 + 16442^2 .

It is a cyclic number.

It is not a de Polignac number, because 644104253 - 2²⁴ = 627327037 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644124253) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24773228 + ... + 24773253.

It is an arithmetic number, because the mean of its divisors is an integer number (173412687).

Almost surely, 2^644104253 is an apocalyptic number.

It is an amenable number.

644104253 is a deficient number, since it is larger than the sum of its proper divisors (49546495).

644104253 is a wasteful number, since it uses less digits than its factorization.

644104253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49546494.

The product of its (nonzero) digits is 11520, while the sum is 29.

The square root of 644104253 is about 25379.2090696302. The cubic root of 644104253 is about 863.6121073496.

Adding to 644104253 its reverse (352401446), we get a palindrome (996505699).

The spelling of 644104253 in words is "six hundred forty-four million, one hundred four thousand, two hundred fifty-three".