644647101213 has 4 divisors (see below), whose sum is σ = 859529468288. Its totient is φ = 429764734140.

The previous prime is 644647101191. The next prime is 644647101221. The reversal of 644647101213 is 312101746446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 644647101213 - 2²⁰ = 644646052637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644647101313) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107441183533 + ... + 107441183538.

It is an arithmetic number, because the mean of its divisors is an integer number (214882367072).

Almost surely, 2^644647101213 is an apocalyptic number.

It is an amenable number.

644647101213 is a deficient number, since it is larger than the sum of its proper divisors (214882367075).

644647101213 is a wasteful number, since it uses less digits than its factorization.

644647101213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214882367074.

The product of its (nonzero) digits is 96768, while the sum is 39.

Adding to 644647101213 its reverse (312101746446), we get a palindrome (956748847659).

The spelling of 644647101213 in words is "six hundred forty-four billion, six hundred forty-seven million, one hundred one thousand, two hundred thirteen".