(*

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

What is the largest prime factor of the number 600851475143 ?

*)

open Big_int;;


(* largest prime factor *)
let lpf =
        let rec factorize i n =
                if(ge_big_int i n)
                then Printf.printf "%s\n" (string_of_big_int n)
                else factorize (succ_big_int i)
                        ( if(eq_big_int (mod_big_int n i) (big_int_of_int 0))
                                then (div_big_int n i) else n )
        in
                factorize (big_int_of_int 2) (big_int_of_string "600851475143")
;;