644294369 has 2 divisors, whose sum is σ = 644294370. Its totient is φ = 644294368.

The previous prime is 644294323. The next prime is 644294381. The reversal of 644294369 is 963492446.

644294369 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 542284369 + 102010000 = 23287^2 + 10100^2 .

It is a cyclic number.

It is not a de Polignac number, because 644294369 - 2⁸ = 644294113 is a prime.

It is a super-2 number, since 2×644294369² = 830230467850216322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (644294309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322147184 + 322147185.

It is an arithmetic number, because the mean of its divisors is an integer number (322147185).

Almost surely, 2^644294369 is an apocalyptic number.

It is an amenable number.

644294369 is a deficient number, since it is larger than the sum of its proper divisors (1).

644294369 is an equidigital number, since it uses as much as digits as its factorization.

644294369 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1119744, while the sum is 47.

The square root of 644294369 is about 25382.9543000810. The cubic root of 644294369 is about 863.6970678858.

The spelling of 644294369 in words is "six hundred forty-four million, two hundred ninety-four thousand, three hundred sixty-nine".