divisible(X,Y) :- 0 is mod(X, Y).

divisible(X,Y) :- X > Y+1, divisible(X, Y+1).

isPrime(2) :- true.
isPrime(X) :- X < 2.
isPrime(X) :- not(divisible(X, 2)).

writePrimes(X) :- X > 1, Y is 1, writePrimes(X, Y).

writePrimes(X, Y) :- X > 1, N is Y + 1, isPrime(N), divisible(X, N), write(N), nl, X1 is X/N, writePrimes(X1).

writePrimes(X, Y) :- X > 1, N is Y + 1, isPrime(N), not(divisible(X, N)), writePrimes(X, N).

writePrimes(X, Y) :-  X > 1, N is Y + 1, not(isPrime(N)), writePrimes(X, N).