644789323 has 4 divisors (see below), whose sum is σ = 644992240. Its totient is φ = 644586408.

The previous prime is 644789293. The next prime is 644789351. The reversal of 644789323 is 323987446.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 323987446 = 2 ⋅161993723.

It is a cyclic number.

It is not a de Polignac number, because 644789323 - 2⁹ = 644788811 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644789023) 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, 96615 + ... + 103072.

It is an arithmetic number, because the mean of its divisors is an integer number (161248060).

Almost surely, 2^644789323 is an apocalyptic number.

644789323 is a deficient number, since it is larger than the sum of its proper divisors (202917).

644789323 is a wasteful number, since it uses less digits than its factorization.

644789323 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 202916.

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

The square root of 644789323 is about 25392.7021602664. The cubic root of 644789323 is about 863.9181784621.

The spelling of 644789323 in words is "six hundred forty-four million, seven hundred eighty-nine thousand, three hundred twenty-three".