644037439 has 4 divisors (see below), whose sum is σ = 644489560. Its totient is φ = 643585320.

The previous prime is 644037437. The next prime is 644037479. The reversal of 644037439 is 934730446.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 644037439 - 2¹ = 644037437 is a prime.

It is a Duffinian number.

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 polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 223917 + ... + 226774.

It is an arithmetic number, because the mean of its divisors is an integer number (161122390).

Almost surely, 2^644037439 is an apocalyptic number.

644037439 is a deficient number, since it is larger than the sum of its proper divisors (452121).

644037439 is a wasteful number, since it uses less digits than its factorization.

644037439 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 452120.

The product of its (nonzero) digits is 217728, while the sum is 40.

The square root of 644037439 is about 25377.8927218160. The cubic root of 644037439 is about 863.5822450127.

The spelling of 644037439 in words is "six hundred forty-four million, thirty-seven thousand, four hundred thirty-nine".