644381190889 has 2 divisors, whose sum is σ = 644381190890. Its totient is φ = 644381190888.

The previous prime is 644381190877. The next prime is 644381190911. The reversal of 644381190889 is 988091183446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 644380269289 + 921600 = 802733^2 + 960^2 .

It is a cyclic number.

It is not a de Polignac number, because 644381190889 - 2¹⁵ = 644381158121 is a prime.

It is a super-2 number, since 2×644381190889² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (644381190829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322190595444 + 322190595445.

It is an arithmetic number, because the mean of its divisors is an integer number (322190595445).

Almost surely, 2^644381190889 is an apocalyptic number.

It is an amenable number.

644381190889 is a deficient number, since it is larger than the sum of its proper divisors (1).

644381190889 is an equidigital number, since it uses as much as digits as its factorization.

644381190889 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11943936, while the sum is 61.

The spelling of 644381190889 in words is "six hundred forty-four billion, three hundred eighty-one million, one hundred ninety thousand, eight hundred eighty-nine".