(27**81) = 8.71e+115 permutations.

I am using a much shorter seed, 27 chars, too lazy to think of more letters. This is only 4.43e+38 permutations. It will take somebody 14 septillion years if they work at at 1 000 000 trillion permutations / second. This is the longest time if they are very unlucky. If we half it for average luck, it's only 7 septillion years for my short seed. A septillion is 24 zeros. I hope the math is correct.