Project Euler (problem 3): Largest Prime Factor

The prime factors of 13195 are 5, 7, 13 and 29.

What is the largest prime factor of the number 600851475143 ?

Solution: growning the factor pairs!

Here's what my solution would look like in Ruby:

 
number = 600851475143
i = 2 

while i * i < number do
  while number % i == 0 do
    number = number / i 
  end 
  i = i + 1 
end

puts number.to_i

Here is the series: