644464363 has 16 divisors (see below), whose sum is σ = 717373440. Its totient is φ = 576417600.

The previous prime is 644464351. The next prime is 644464391. The reversal of 644464363 is 363464446.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 644464363 - 2⁹ = 644463851 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644464333) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10806 + ... + 37492.

It is an arithmetic number, because the mean of its divisors is an integer number (44835840).

Almost surely, 2^644464363 is an apocalyptic number.

644464363 is a deficient number, since it is larger than the sum of its proper divisors (72909077).

644464363 is a wasteful number, since it uses less digits than its factorization.

644464363 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26778.

The product of its digits is 497664, while the sum is 40.

The square root of 644464363 is about 25386.3026650200. The cubic root of 644464363 is about 863.7730219918.

It can be divided in two parts, 6444 and 64363, that added together give a palindrome (70807).

The spelling of 644464363 in words is "six hundred forty-four million, four hundred sixty-four thousand, three hundred sixty-three".