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

The prime factorization of 81,20, and 77 is 124740. Thanks for using ChaCha!!
http://www.chacha.com/question/whatistheprimef...

The only prime dividing 81 is 3, since 81=3^4. 108 factors as 2^2 times 3^3. Then the two numbers have the prime 3 in common. I believe this should be the answer, based on the wording
http://answers.yahoo.com/question/index?qid=200905...

1001 = 7 x 11 x 13.
http://wiki.answers.com/Q/What_is_the_prime_factor...
