644031606013 has 2 divisors, whose sum is σ = 644031606014. Its totient is φ = 644031606012.

The previous prime is 644031605993. The next prime is 644031606019. The reversal of 644031606013 is 310606130446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 387952088164 + 256079517849 = 622858^2 + 506043^2 .

It is a cyclic number.

It is not a de Polignac number, because 644031606013 - 2²⁵ = 643998051581 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644031606013.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644031606019) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322015803006 + 322015803007.

It is an arithmetic number, because the mean of its divisors is an integer number (322015803007).

Almost surely, 2^644031606013 is an apocalyptic number.

It is an amenable number.

644031606013 is a deficient number, since it is larger than the sum of its proper divisors (1).

644031606013 is an equidigital number, since it uses as much as digits as its factorization.

644031606013 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 31104, while the sum is 34.

Adding to 644031606013 its reverse (310606130446), we get a palindrome (954637736459).

The spelling of 644031606013 in words is "six hundred forty-four billion, thirty-one million, six hundred six thousand, thirteen".