644313647 has 16 divisors (see below), whose sum is σ = 677376000. Its totient is φ = 612212160.

The previous prime is 644313629. The next prime is 644313667. The reversal of 644313647 is 746313446.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 644313647 - 2¹⁰ = 644312623 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644313647.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644313667) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 459854 + ... + 461252.

It is an arithmetic number, because the mean of its divisors is an integer number (42336000).

Almost surely, 2^644313647 is an apocalyptic number.

644313647 is a deficient number, since it is larger than the sum of its proper divisors (33062353).

644313647 is a wasteful number, since it uses less digits than its factorization.

644313647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1726.

The product of its digits is 145152, while the sum is 38.

The square root of 644313647 is about 25383.3340402714. The cubic root of 644313647 is about 863.7056820570.

The spelling of 644313647 in words is "six hundred forty-four million, three hundred thirteen thousand, six hundred forty-seven".