644727216589 has 2 divisors, whose sum is σ = 644727216590. Its totient is φ = 644727216588.

The previous prime is 644727216587. The next prime is 644727216677. The reversal of 644727216589 is 985612727446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 627842293225 + 16884923364 = 792365^2 + 129942^2 .

It is a cyclic number.

It is not a de Polignac number, because 644727216589 - 2¹ = 644727216587 is a prime.

Together with 644727216587, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644727216587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322363608294 + 322363608295.

It is an arithmetic number, because the mean of its divisors is an integer number (322363608295).

Almost surely, 2^644727216589 is an apocalyptic number.

It is an amenable number.

644727216589 is a deficient number, since it is larger than the sum of its proper divisors (1).

644727216589 is an equidigital number, since it uses as much as digits as its factorization.

644727216589 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 40642560, while the sum is 61.

The spelling of 644727216589 in words is "six hundred forty-four billion, seven hundred twenty-seven million, two hundred sixteen thousand, five hundred eighty-nine".