644644238 has 16 divisors (see below), whose sum is σ = 1105432704. Its totient is φ = 276194040.

The previous prime is 644644213. The next prime is 644644289. The reversal of 644644238 is 832446446.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 644644195 and 644644204.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 79973 + ... + 87663.

It is an arithmetic number, because the mean of its divisors is an integer number (69089544).

Almost surely, 2^644644238 is an apocalyptic number.

644644238 is a deficient number, since it is larger than the sum of its proper divisors (460788466).

644644238 is a wasteful number, since it uses less digits than its factorization.

644644238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13687.

The product of its digits is 442368, while the sum is 41.

The square root of 644644238 is about 25389.8451747938. The cubic root of 644644238 is about 863.8533764321.

The spelling of 644644238 in words is "six hundred forty-four million, six hundred forty-four thousand, two hundred thirty-eight".