Regular polytopes, sphere packings and Apollonian sections

In this paper, we explore the geometry and the arithmetic of a family of polytopal sphere packings induced by regular polytopes. We prove that every integral polytope is crystallographic and we show that there are 11 crystallographic regular polytopes in any dimension. After introducing the notion of Apollonian section, we study which Platonic crystallographic packings emerge as cross sections of the Apollonian arrangements of the regular 4-polytopes. Additionally, we compute the Möbius spectrum of every regular polytope.