...IOW, this asteroid is approximately EIGHT times (at least twice in each of three dimensions) more massive than the Barringer object that made Meteor/Barringer Crater — enough to make a crater eight times the size. If it hit in, say, Chicago, the crater would be roughly two miles across (sq root of 8, 2.828427125 times .75 miles), and the shock wave would knock down everything else for many miles in all directions.
Of course, we’d better not take my word for it...
I dunno. I don’t think anyone knows for sure what the consequences of a collision would be, but the 2.2MT is a guesstimate of the available energy. Depends on the mass of the object, its orbit and the collision geometry.