5Improved Answer:-An heptagon has 7 sides but a pentagon has 5 sides
Heptagonal is an adjective: the answer depends on the noun that it refers to. A heptagonal pyramid, a heptagonal dipyramid or a heptagonal prism or some other heptagonal shape?
Heptagonal is an adjective, not a noun! The answer will depend on whether you mean a heptagonal pyramid, a heptagonal bipyramid, a heptagonal prism or whatever.
there is 13 edges in a heptagonal pyramid.
A heptagon is a 7-sided polygon, so a heptagonal prism is a 3D version of that (9 sides, 21 edges, 14 vertices).
a heptagonal pyramid has 8 faces
A heptagonal prism has two 7-sided bases.
A heptagonal what? Prism, pyramid or something else?