The method I provided finds the *factors* of N, not the prime factors,
and only up to an N of 65,536 at that, unless you are willing to forego
N itself, in which case it can be modified to go higher, to 131,072.
Sorry about that, I didn't read your post properly. You can find a
method of finding factors here

http://tinyurl.com/dljjt

using VBA. This also has a macro for finding the primes up to a given
number. You may be able to combine the two methods to get the prime
factors.

FWIW, there is a program available here

http://tinyurl.com/aleae

for computing prime factors.

I hope THIS helps, as opposed to my previous post.

I'll take another look at it to see if I can find or determine another
approach.

Declan O'R