While it appears that n# is a trivial thing to consider, nevertheless it has some bizarre (and unlooked-for) properties, such as the following (from http://mathworld.wolfram.com/Primorial.html):
1/p(n)
lim (p(n)#) = e
n->∞
In the above relation, p(n) is the largest prime less than or equal to n, and e is Napier's number (which is more commonly known as Euler's number).