644341513 has 2 divisors, whose sum is σ = 644341514. Its totient is φ = 644341512.

The previous prime is 644341507. The next prime is 644341549. The reversal of 644341513 is 315143446.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 373146489 + 271195024 = 19317^2 + 16468^2 .

It is a cyclic number.

It is not a de Polignac number, because 644341513 - 2²⁵ = 610787081 is a prime.

It is not a weakly prime, because it can be changed into another prime (644341553) 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, 322170756 + 322170757.

It is an arithmetic number, because the mean of its divisors is an integer number (322170757).

Almost surely, 2^644341513 is an apocalyptic number.

It is an amenable number.

644341513 is a deficient number, since it is larger than the sum of its proper divisors (1).

644341513 is an equidigital number, since it uses as much as digits as its factorization.

644341513 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17280, while the sum is 31.

The square root of 644341513 is about 25383.8829378013. The cubic root of 644341513 is about 863.7181333819.

Adding to 644341513 its reverse (315143446), we get a palindrome (959484959).

The spelling of 644341513 in words is "six hundred forty-four million, three hundred forty-one thousand, five hundred thirteen".