644220959 has 2 divisors, whose sum is σ = 644220960. Its totient is φ = 644220958.

The previous prime is 644220953. The next prime is 644220977. The reversal of 644220959 is 959022446.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644220959 - 2¹² = 644216863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644220953) 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, 322110479 + 322110480.

It is an arithmetic number, because the mean of its divisors is an integer number (322110480).

Almost surely, 2^644220959 is an apocalyptic number.

644220959 is a deficient number, since it is larger than the sum of its proper divisors (1).

644220959 is an equidigital number, since it uses as much as digits as its factorization.

644220959 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 155520, while the sum is 41.

The square root of 644220959 is about 25381.5082097183. The cubic root of 644220959 is about 863.6642638276.

The spelling of 644220959 in words is "six hundred forty-four million, two hundred twenty thousand, nine hundred fifty-nine".