A crystalline solid of a pure substance has a face-centered cubic structure with a cell edge of $$400$$ $$pm.$$ If the density of the substance in the crystal is $$8$$ $$g\,c{m^{ - 3}},$$ then the number of atoms present in $$256$$ $$g$$ of the crystal is $$N \times {10^{24}}.$$ The value of $$N$$ is

The number of hexagonal faces that are present in a truncated octahedron is ____________.