The hammer was "forged from a collapsing star" according to comic book legend, which Tyson claims means it clocks in at the equivalent rate of about "300 billion elephants." So that's 4.5 quadrillion pounds, if you're counting with your hands. In which case, stop, and go back to using "billions of elephants" as your measurement unit of choice.
So, yeah, Thor will definitely want to check that baby in baggage claim next time he boards a flight. (And, no, no one is going to steal it. It weighs 300 billion elephants, for the Gods's sake!)