644364423 has 24 divisors (see below), whose sum is σ = 1007516400. Its totient is φ = 406960848.

The previous prime is 644364421. The next prime is 644364437. The reversal of 644364423 is 324463446.

644364423 is a `hidden beast` number, since 6 + 4 + 4 + 3 + 644 + 2 + 3 = 666.

It is not a de Polignac number, because 644364423 - 2¹ = 644364421 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644364421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 23308 + ... + 42801.

It is an arithmetic number, because the mean of its divisors is an integer number (41979850).

Almost surely, 2^644364423 is an apocalyptic number.

644364423 is a deficient number, since it is larger than the sum of its proper divisors (363151977).

644364423 is a wasteful number, since it uses less digits than its factorization.

644364423 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66156 (or 66131 counting only the distinct ones).

The product of its digits is 165888, while the sum is 36.

The square root of 644364423 is about 25384.3342043868. The cubic root of 644364423 is about 863.7283699555.

The spelling of 644364423 in words is "six hundred forty-four million, three hundred sixty-four thousand, four hundred twenty-three".