The internationally agreed symbol for 10^6 is M and this is the initial letter of million. Would it not be logical and convenient to turn this happy accident into a principle and use G, the internationally agreed symbol for 10^9, as the initial letter of the word for 1,000,000,000? That number would thus be called a gillion. Whether the g should be hard or soft is a matter of opinion. I incline to hard because of the derivation from giga.
Source: wiktionary
At Guy's school there had been an outdoor pool, in use from April to October, a watery grave for a billion insects, or quite possibly a gillion or a squillion. The bright turquoise lining had wrinkled under the children's feet.
Source: wiktionary
I looked down to see my dog, Roof, short for Rufus, curled in sleep below the window, unworried by the wings of hummingbirds whirring at speeds of a gillion miles an hour as they flitted in and out of the trumpets of honeysuckle growing on the side of the house.
Source: wiktionary