644355269 has 2 divisors, whose sum is σ = 644355270. Its totient is φ = 644355268.

The previous prime is 644355247. The next prime is 644355277. The reversal of 644355269 is 962553446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 452200225 + 192155044 = 21265^2 + 13862^2 .

It is a cyclic number.

It is not a de Polignac number, because 644355269 - 2¹⁶ = 644289733 is a prime.

It is a super-2 number, since 2×644355269² = 830387425376124722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644355169) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322177634 + 322177635.

It is an arithmetic number, because the mean of its divisors is an integer number (322177635).

Almost surely, 2^644355269 is an apocalyptic number.

It is an amenable number.

644355269 is a deficient number, since it is larger than the sum of its proper divisors (1).

644355269 is an equidigital number, since it uses as much as digits as its factorization.

644355269 is an evil number, because the sum of its binary digits is even.

The product of its digits is 777600, while the sum is 44.

The square root of 644355269 is about 25384.1538956885. The cubic root of 644355269 is about 863.7242798233.

The spelling of 644355269 in words is "six hundred forty-four million, three hundred fifty-five thousand, two hundred sixty-nine".