644671123 has 4 divisors (see below), whose sum is σ = 647122608. Its totient is φ = 642219640.

The previous prime is 644671087. The next prime is 644671169. The reversal of 644671123 is 321176446.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 644671123 - 2²⁹ = 107800211 is a prime.

It is a super-2 number, since 2×644671123² = 831201713660162258, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644671723) 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, 1225348 + ... + 1225873.

It is an arithmetic number, because the mean of its divisors is an integer number (161780652).

Almost surely, 2^644671123 is an apocalyptic number.

644671123 is a deficient number, since it is larger than the sum of its proper divisors (2451485).

644671123 is a wasteful number, since it uses less digits than its factorization.

644671123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2451484.

The product of its digits is 24192, while the sum is 34.

The square root of 644671123 is about 25390.3746132270. The cubic root of 644671123 is about 863.8653853169.

The spelling of 644671123 in words is "six hundred forty-four million, six hundred seventy-one thousand, one hundred twenty-three".