[quote=Schradinger]
Wouldn't it be a 17,200 megaton explosion? Since the maximum yield of one kiloton of matter being annihilated is 21.5 megatons, and apparently half that gets released as neutrinos in proton-antiproton annihilation. Assuming Wikipedia hasn't been ninja'd.
[/quote]

One kiloton makes a whole lot more energy than that!

Just do E=MC^2