If my math is correct the impact would be equivalent to ~65 megaton bomb.
Do you mean, "if I'm quoting a reliable source" or did you actually do the math to calculate this?
Tsar Bomba, mentioned above, was about 50 megatons. Wiki has a decent article to give an idea of the amount of damage it would cause
here Russia had/has the capability of producing a much stronger bomb, but there's no military reason to have such a strong weapon.
But, (and I'm not going to attempt the calculations; it's simpler to just quote someone who has all the necessary numbers - mass, impact velocity, etc.) it's fairly simple to find estimates of the energy. Wiki, for example, places it at
880 megatons. An order of magnitude worse than what you calculated. (or rather, that's according to NASA calculations) Furthermore, if anyone is familiar with the comet/asteroid that exploded above Siberia (Tunguska event), you'll have a good idea how powerful 50 or 65 or 880 megatons is. The Tunguska event felled an estimated 60 million trees over 2,150 square kilometers (830 sq mi)." The Tunguska event is estimated at 10-15 megatons. Had that event occured just an hour or so later at the same latitude, it would have obliterated St. Petersburg.
Personally, I think it'd be pretty cool to get to experience a smaller impact on this planet (just as long as it hit a remote unpopulated area). It was incredibly interesting when the comet Shoemaker-Levy broke up and smacked Jupiter.