644646123 has 12 divisors (see below), whose sum is σ = 1015806168. Its totient is φ = 390694560.

The previous prime is 644646097. The next prime is 644646169. The reversal of 644646123 is 321646446.

644646123 is a `hidden beast` number, since 6 + 4 + 4 + 646 + 1 + 2 + 3 = 666.

644646123 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 644646123 - 2⁵ = 644646091 is a prime.

It is a super-2 number, since 2×644646123² = 831137247797862258, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (644646173) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3255690 + ... + 3255887.

It is an arithmetic number, because the mean of its divisors is an integer number (84650514).

Almost surely, 2^644646123 is an apocalyptic number.

644646123 is a deficient number, since it is larger than the sum of its proper divisors (371160045).

644646123 is a wasteful number, since it uses less digits than its factorization.

644646123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6511594 (or 6511591 counting only the distinct ones).

The product of its digits is 82944, while the sum is 36.

The square root of 644646123 is about 25389.8822959068. The cubic root of 644646123 is about 863.8542184273.

The spelling of 644646123 in words is "six hundred forty-four million, six hundred forty-six thousand, one hundred twenty-three".