644464326 has 32 divisors (see below), whose sum is σ = 1416240000. Its totient is φ = 193884480.

The previous prime is 644464307. The next prime is 644464333. The reversal of 644464326 is 623464446.

It is a Curzon number.

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 15 ways as a sum of consecutive naturals, for example, 25951 + ... + 44298.

It is an arithmetic number, because the mean of its divisors is an integer number (44257500).

Almost surely, 2^644464326 is an apocalyptic number.

644464326 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

644464326 is an abundant number, since it is smaller than the sum of its proper divisors (771775674).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644464326 is a wasteful number, since it uses less digits than its factorization.

644464326 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70404.

The product of its digits is 331776, while the sum is 39.

The square root of 644464326 is about 25386.3019362805. The cubic root of 644464326 is about 863.7730054615.

The spelling of 644464326 in words is "six hundred forty-four million, four hundred sixty-four thousand, three hundred twenty-six".