I did not know that yesterday!

The big numbers past a trillion, in ascending powers of ten, are as follows: quadrillion, quintillion, sextillion, septillion, octillion, nonillion, decillion, undecillion, duodecillion, tredecillion, quattuordecillion, and quindecillion (that's 10 to the 48th, or a one followed by 48 zeros). But wait -- there's more.
The highest number listed on Robert Munafo's table, which coincidentally is my new favorite number, is a milli-millillion. Say that three times fast! That's 10 to the 3000003rd. For something closer to home, a centillion is 10 to the 303rd.

The googolplex has often been nominated as the largest named number in the world. If a googol is ten to the one hundredth, then a googolplex is one followed by a googol of zeroes. Ugh, we think we feel a headache coming on.

The aforementioned mathematician and large number fan Robert Munafo offers a table of megadigits on his personal page. You'll also find some biggies at Russ Rowlett's page at the University of North Carolina.