171 (number)

171 is the natural number following 170 and preceding 172.

In mathematics

171 is the 18th triangular number and a Jacobsthal number.
There are 171 transitive relations on three labeled elements, and 171 combinatorially distinct ways of subdividing a cuboid by flat cuts into a mesh of tetrahedra, without adding extra vertices.
The diagonals of a regular decagon meet at 171 points, including both crossings and the vertices of the decagon.
There are 171 faces and edges in the 57-cell, an abstract 4-polytope with hemi-dodecahedral cells that is its own dual polytope.
Within moonshine theory of sporadic groups, the friendly giant is defined as having cyclic groups ⟨ ⟩ that are linked with the function,
This generates 171 moonshine groups within associated with that are principal moduli for different genus zero congruence groups commensurable with the projective linear group.