Today I found the factor:
P-1 found a factor in stage #2, B1=130000, B2=2200000.
21181*2^16496492+1 has a factor: 13825033371936547

But I will not get any credit for it because user 13796 (PrimeGrid) already found this factor.
I found that out here: http://www.seventeenorbust.com/sieve/results.txt.bz2
I searched for more tests with already found factors in my worktodo.txt and found another two already found factors by PrimeGrid. So I deleted them from the worktodo.txt.

How can I prevent PrimeGrid finding my factors first?