Thirty-three was when Jesus supposedly died, and many celebrities seem partial to kicking it when they're twenty-seven (for whatever reason), so those numbers, along with the major decades (twenty, thirty, forty, etc.) as well as the half-decades (twenty-five, thirty-five, etc.) have their own sort of milestone quality.
Forty-two has the benefit of being the ultimate answer to life, the universe and everything (neeeeerrrrrrddd!) but the only thing that forty-three seems to have going for it is that it's a natural number greater than 1 that has no positive divisors other than 1 and itself.