644968459 has 2 divisors, whose sum is σ = 644968460. Its totient is φ = 644968458.

The previous prime is 644968453. The next prime is 644968477. The reversal of 644968459 is 954869446.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644968459 - 2²⁷ = 510750731 is a prime.

It is not a weakly prime, because it can be changed into another prime (644968453) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322484229 + 322484230.

It is an arithmetic number, because the mean of its divisors is an integer number (322484230).

Almost surely, 2^644968459 is an apocalyptic number.

644968459 is a deficient number, since it is larger than the sum of its proper divisors (1).

644968459 is an equidigital number, since it uses as much as digits as its factorization.

644968459 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7464960, while the sum is 55.

The square root of 644968459 is about 25396.2292279779. The cubic root of 644968459 is about 863.9981759185.

The spelling of 644968459 in words is "six hundred forty-four million, nine hundred sixty-eight thousand, four hundred fifty-nine".