Not long after we started blogging in 2008, we started to dive into our fascination with the Upper Peninsula's exclusive area code, 906. At the time, though it was widely known to be exclusive to the U.P., it was not seen as a recognizable symbol of the region. Since our founding we've helped change that, and 906 is nearly as recognizable to our identity as the word Yooper. Did you know 906 is a sphenic number? That's right, a positive integer that is the product of three distinct prime num…