20160 is the smallest order with more than one simple group. One of them is the alternating group of degree 8, which is isomorphic to the matrix groups GL(4,2), PGL(4,2), PSL(4,2), and SL(4,2). The other is the Mathieu group of degree 21, which is isomorphic to the matrix group PSL(3,4). It is also the number of minutes in a fortnight.