644338903 has 16 divisors (see below), whose sum is σ = 714067200. Its totient is φ = 577624320.

The previous prime is 644338897. The next prime is 644338927. The reversal of 644338903 is 309833446.

It is a de Polignac number, because none of the positive numbers 2^k-644338903 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 (644338943) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 119418 + ... + 124696.

It is an arithmetic number, because the mean of its divisors is an integer number (44629200).

Almost surely, 2^644338903 is an apocalyptic number.

644338903 is a deficient number, since it is larger than the sum of its proper divisors (69728297).

644338903 is a wasteful number, since it uses less digits than its factorization.

644338903 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5562.

The product of its (nonzero) digits is 186624, while the sum is 40.

The square root of 644338903 is about 25383.8315271749. The cubic root of 644338903 is about 863.7169671746.

The spelling of 644338903 in words is "six hundred forty-four million, three hundred thirty-eight thousand, nine hundred three".