644259265513 has 2 divisors, whose sum is σ = 644259265514. Its totient is φ = 644259265512.

The previous prime is 644259265457. The next prime is 644259265519. The reversal of 644259265513 is 315562952446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 428988320784 + 215270944729 = 654972^2 + 463973^2 .

It is a cyclic number.

It is not a de Polignac number, because 644259265513 - 2³³ = 635669330921 is a prime.

It is not a weakly prime, because it can be changed into another prime (644259265519) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322129632756 + 322129632757.

It is an arithmetic number, because the mean of its divisors is an integer number (322129632757).

Almost surely, 2^644259265513 is an apocalyptic number.

It is an amenable number.

644259265513 is a deficient number, since it is larger than the sum of its proper divisors (1).

644259265513 is an equidigital number, since it uses as much as digits as its factorization.

644259265513 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7776000, while the sum is 52.

The spelling of 644259265513 in words is "six hundred forty-four billion, two hundred fifty-nine million, two hundred sixty-five thousand, five hundred thirteen".