13! is above int32.MaxValue.

I don't know without looking at the code, but

    4 years = 126144000 seconds
   67 days  =   5788800 seconds
    3 hours =     10800 seconds
 48 minutes =      2880 seconds
 56 seconds =        56 seconds
 ------------------------------
   Total    =  131946536

that is not 132030240.