Quote:
Originally Posted by mattmill30
Can someone explain why M397 is labeled as fully factored

Two answers.
1) Because it is.
2) Lazy programmer.
In this particular case, all the factors are small and proven prime, but in the general case, a fullyfactored exponent will result from a bunch of small factors and a large PRP cofactor. We're confident that the PRP cofactor is prime, but it will not be mathematically proven. There is no separate logic in the website to handle when the last factor is proven vs PRP.