A nonillion.
1 followed by 18 zeros is a quintillion.
A nonillion.
That depends how many zeros follow the 1.
1 decillion
A quindecillion.
It's a googolplex
That's a tredecillion!
1 followed by 100 zeros is called a google.
A nonillion is equal to 1 followed by 30 zeros. This is because nonillion is the number 1 with 30 groups of three zeros after it. Each group of three zeros represents a power of 10 (thousand, million, billion, etc.), so in total, a nonillion has 30 zeros.
If you meant a number followed by 100 zeros, that would be Google if the number was a 1. If you meant 100 zeros followed by a number, that would be just that number.
I call it "ten to the fifty-two", and I write it like this: 1052
1 sextillion 1 septillion 1 octillion