644335544 has 16 divisors (see below), whose sum is σ = 1209766320. Its totient is φ = 321731200.

The previous prime is 644335537. The next prime is 644335561. The reversal of 644335544 is 445533446.

It is a junction number, because it is equal to n+sod(n) for n = 644335498 and 644335507.

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 3 ways as a sum of consecutive naturals, for example, 48257 + ... + 60144.

It is an arithmetic number, because the mean of its divisors is an integer number (75610395).

Almost surely, 2^644335544 is an apocalyptic number.

It is an amenable number.

644335544 is a deficient number, since it is larger than the sum of its proper divisors (565430776).

644335544 is a wasteful number, since it uses less digits than its factorization.

644335544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109150 (or 109146 counting only the distinct ones).

The product of its digits is 345600, while the sum is 38.

The square root of 644335544 is about 25383.7653629244. The cubic root of 644335544 is about 863.7154662924.

The spelling of 644335544 in words is "six hundred forty-four million, three hundred thirty-five thousand, five hundred forty-four".