3 x 3 x 3 x 3.
http://wiki.answers.com/Q/What_is_the_prime_factor...

Well I guess that would be 3^4 or 3*3*3*3
http://www.chacha.com/question/whatistheprimef...

81 = 9 * 9 = 3 * 3 * 3 *3. All the 3's are prime numbers no longer factorable.
http://answers.yahoo.com/question/index?qid=201308...

1. Start off by dividing out any 2's, since it's easy to see if your number can be divided by 2. Specifically, look at the "ones place. If there is a 0, 2, 4, 6, or 8 in that
http://www.ehow.com/how_5946201_calculateprimefa...
