In this talk, I will try to summarize our recent work on the partition function of the ABJM theory, which describes the worldvolume theory of N coincident M2-branes. To make the subject more accessible, I will present it using the formulation that rewrites the ABJM partition function into that of a non-interacting ideal Fermi gas system. The one-particle Hamiltonian of this fermion can be regarded as a deformation from that of the harmonic oscillator and is mathematically interesting by itself. I will present our results on the explicit large N expansion of the ABJM partition function including all of the non-perturbative corrections and explain their physical interpretation.