For this number, I don’t see any obvious special form. This leaves basically 2 choices: ECM, and GNFS.

Since you say that the number is likely to factor as 2 P100’s, ECM is very unlikely to get a factor (unless you are lucky). So your best bet would be to use GNFS.

This graph gives an idea as to how long GNFS jobs take for different size inputs. Using the best fit curve, time=5*10^((number of digits/20)-5), you are looking at about 500000 CPU hours to factor this composite.