644577438 has 16 divisors (see below), whose sum is σ = 1345205376. Its totient is φ = 205517400.

The previous prime is 644577433. The next prime is 644577443. The reversal of 644577438 is 834775446.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (644577433) and next prime (644577443).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644577431) 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 7 ways as a sum of consecutive naturals, for example, 2335288 + ... + 2335563.

It is an arithmetic number, because the mean of its divisors is an integer number (84075336).

Almost surely, 2^644577438 is an apocalyptic number.

644577438 is an abundant number, since it is smaller than the sum of its proper divisors (700627938).

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

644577438 is a wasteful number, since it uses less digits than its factorization.

644577438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4670879.

The product of its digits is 2257920, while the sum is 48.

The square root of 644577438 is about 25388.5296541568. The cubic root of 644577438 is about 863.8235370284.

The spelling of 644577438 in words is "six hundred forty-four million, five hundred seventy-seven thousand, four hundred thirty-eight".