Obviously all of Egan’s work is math heavy. But my favourite of them is Diaspora. The characters navigate differential geometry and higher dimensional topology in a matter-of-fact manner.
Another famous one, a murder mystery that uses math well, is Devotion of Suspect X. Blindspots in search space algorithms are used to craft the perfect murder in this one. Won’t spoil it further.
Do you dream of saving the world by solving problems on euclidean geometry? That’s the superhero alternative explored in Anathem. In a way, it’s like fanfiction for all the American armageddon movies written by polymaths.