644960420173 has 4 divisors (see below), whose sum is σ = 644981005440. Its totient is φ = 644939834908.

The previous prime is 644960420171. The next prime is 644960420189. The reversal of 644960420173 is 371024069446.

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 a cyclic number.

It is not a de Polignac number, because 644960420173 - 2¹ = 644960420171 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 (644960420171) 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, 10245565 + ... + 10308322.

It is an arithmetic number, because the mean of its divisors is an integer number (161245251360).

Almost surely, 2^644960420173 is an apocalyptic number.

It is an amenable number.

644960420173 is a deficient number, since it is larger than the sum of its proper divisors (20585267).

644960420173 is a wasteful number, since it uses less digits than its factorization.

644960420173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20585266.

The product of its (nonzero) digits is 870912, while the sum is 46.

The spelling of 644960420173 in words is "six hundred forty-four billion, nine hundred sixty million, four hundred twenty thousand, one hundred seventy-three".