In a 10 lb bag of Idaho® russets I found a HUGE potato, bigger than any potato I've ever cooked! I don't want to cut it up, but I have no idea how long to bake it.  I measured it...it is more than 6 inches long, with a slightly more than 9-inch circumference.

How long and at what temperature should I bake it at? Any special instructions?

It should take a little more than an hour to bake at 400°F. The internal temperature needs to be at least 185°F, and it’s done at 210°F.  Use a meat thermometer and place it in the middle of the potato to measure.

http://www.averagebetty.com/recipes/monster-baked-potato-recipe-and-tips/