I think most of us are impressed by computational parlor tricks (and indeed raw computational intelligence in general -- being able to process information and compute quickly and accurately), but for me, genius goes beyond that.

Genius is about having rare and useful insights that the rest of us are incapable of, and that a computer is unable to easily replicate.

For instance, there was this thing on Twitter recently about all percentages being reversible (7% of 50 is equal to 50% of 7, but the latter is easier to mentally calculate). Most of us are aware that multiplication is commutative, but it takes genius to recognize and frame that insight in a useful way.