644037438 has 16 divisors (see below), whose sum is σ = 1405172736. Its totient is φ = 195162840.

The previous prime is 644037437. The next prime is 644037479. The reversal of 644037438 is 834730446.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 644037396 and 644037405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644037437) 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, 4879006 + ... + 4879137.

It is an arithmetic number, because the mean of its divisors is an integer number (87823296).

Almost surely, 2^644037438 is an apocalyptic number.

644037438 is an abundant number, since it is smaller than the sum of its proper divisors (761135298).

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

644037438 is a wasteful number, since it uses less digits than its factorization.

644037438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9758159.

The product of its (nonzero) digits is 193536, while the sum is 39.

The square root of 644037438 is about 25377.8927021138. The cubic root of 644037438 is about 863.5822445658.

The spelling of 644037438 in words is "six hundred forty-four million, thirty-seven thousand, four hundred thirty-eight".