Demified icosiheptaheptacontadipeton

The demified icosiheptaheptacontadipeton or hejak, also called the demified 221 polytope, is a convex uniform polypeton. It consists of 27 small prismated demipenteracts, 27 demipenteracts, 72 hexatera, and 216 pentachoric prisms. 5 small prismated demipenteracts, 1 demipenteract, 1 hexateron, and 5 pentachoric prisms join at each vertex.

The demified icosiheptaheptacontadipeton contains the vertices and edges of the bitruncated hexateric prism.