644956369 has 2 divisors, whose sum is σ = 644956370. Its totient is φ = 644956368.

The previous prime is 644956343. The next prime is 644956373. The reversal of 644956369 is 963659446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 345216400 + 299739969 = 18580^2 + 17313^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644956369 is a prime.

It is a super-2 number, since 2×644956369² = 831937435827328322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (644956339) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322478184 + 322478185.

It is an arithmetic number, because the mean of its divisors is an integer number (322478185).

Almost surely, 2^644956369 is an apocalyptic number.

It is an amenable number.

644956369 is a deficient number, since it is larger than the sum of its proper divisors (1).

644956369 is an equidigital number, since it uses as much as digits as its factorization.

644956369 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4199040, while the sum is 52.

The square root of 644956369 is about 25395.9911994000. The cubic root of 644956369 is about 863.9927773066.

The spelling of 644956369 in words is "six hundred forty-four million, nine hundred fifty-six thousand, three hundred sixty-nine".