2 + 1 = 3 (algebraic factor) *
And the factorization is:
The factorization was achieved using 8 SUN-3/75 computers running in parallel.
Total computation time summed over all machines was 1260 hours.
This number is interesting because it is the smallest known number of the
form 2^n + 1 that has not been completely factorized and in fact had no
known factors other than the trivial algebraic factor 3.