Centillion

[Gregory]

Centillion Is 1 Followed by [303] zeros!

[Becky]

Originally: the cardinal number equal to the hundredth power of a million, represented by 1 followed by six hundred zeros (now chiefly British). Later also (originally US): the cardinal number equal to the hundred and first power of a thousand, represented by 1 followed by three hundred and three zeros. Also hyperbolically: a very large number or amount.

[Tracie Lynn]

Largest [number] that is actually utilized by [scientists]. It is 1 followed by [600] zeros