What will going tofollow to pentillions?

Answer 1

A pentillion was the name proposed for what is not known as a quadrillion = 10^15.

This was necessitated by the confusion between the US and European use of billion (thousand million or million million) and higher numbers. New names, based on Greek roots, were proposed. In many countries the European names have now been dropped in favour of the US names.

So the next term would have been a hextillion.