644355261323 has 8 divisors (see below), whose sum is σ = 648484306848. Its totient is φ = 640226530944.

The previous prime is 644355261313. The next prime is 644355261349. The reversal of 644355261323 is 323162553446.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644355261323 - 2²⁸ = 644086825867 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644355261313) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5116115 + ... + 5240547.

It is an arithmetic number, because the mean of its divisors is an integer number (81060538356).

Almost surely, 2^644355261323 is an apocalyptic number.

644355261323 is a deficient number, since it is larger than the sum of its proper divisors (4129045525).

644355261323 is a wasteful number, since it uses less digits than its factorization.

644355261323 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157573.

The product of its digits is 1555200, while the sum is 44.

The spelling of 644355261323 in words is "six hundred forty-four billion, three hundred fifty-five million, two hundred sixty-one thousand, three hundred twenty-three".