644304435013 has 2 divisors, whose sum is σ = 644304435014. Its totient is φ = 644304435012.

The previous prime is 644304434993. The next prime is 644304435031. The reversal of 644304435013 is 310534403446.

Together with next prime (644304435031) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 597655778724 + 46648656289 = 773082^2 + 215983^2 .

It is a cyclic number.

It is not a de Polignac number, because 644304435013 - 2⁵ = 644304434981 is a prime.

It is a super-2 number, since 2×644304435013² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644304439013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322152217506 + 322152217507.

It is an arithmetic number, because the mean of its divisors is an integer number (322152217507).

Almost surely, 2^644304435013 is an apocalyptic number.

It is an amenable number.

644304435013 is a deficient number, since it is larger than the sum of its proper divisors (1).

644304435013 is an equidigital number, since it uses as much as digits as its factorization.

644304435013 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 207360, while the sum is 37.

Adding to 644304435013 its reverse (310534403446), we get a palindrome (954838838459).

The spelling of 644304435013 in words is "six hundred forty-four billion, three hundred four million, four hundred thirty-five thousand, thirteen".