anakin+reyna
But not if you stay here, right? You can cheat death by staying here.
Not entirely? But there was a prophecy about the child of one of the big three - Zeus, Poseidon, & Hades - turning 16. So some of them did things to stop the aging process - like joining the greek equivalent of the amazons, Hades putting Nico & Bianca in the time bubble, etc. But then it came to fruition with Percy, so Nico's safe from that one now..
Basically you usually only know the birthdays of demigods if it's something bad.