Does anyone know this old children's/teen's book?

I can't remember the title of it. But I remember: it's about a princess who is decidedly odd. Well, odd seeming in the medieval world she inhabits, she winds up being abducted by a dragon, in which case she likes living with the dragon and tidies up after her treasure hordes. She turns down knights that want to save her, one time sending one to another princess that was also captive. She one time thwarts a genie/jinnie that wants to kill her and outsmarts it by choosing to die of old age. If this rings any bells, I'd LOVE to know the title. Thanks!