644123423 has 2 divisors, whose sum is σ = 644123424. Its totient is φ = 644123422.

The previous prime is 644123393. The next prime is 644123449. The reversal of 644123423 is 324321446.

644123423 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644123423 - 2⁸ = 644123167 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644123453) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322061711 + 322061712.

It is an arithmetic number, because the mean of its divisors is an integer number (322061712).

Almost surely, 2^644123423 is an apocalyptic number.

644123423 is a deficient number, since it is larger than the sum of its proper divisors (1).

644123423 is an equidigital number, since it uses as much as digits as its factorization.

644123423 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13824, while the sum is 29.

The square root of 644123423 is about 25379.5867381642. The cubic root of 644123423 is about 863.6206749481.

Adding to 644123423 its reverse (324321446), we get a palindrome (968444869).

The spelling of 644123423 in words is "six hundred forty-four million, one hundred twenty-three thousand, four hundred twenty-three".