What is the value of twenty-one zeros?

Answer 1

Are you asking what is the number called if it has a 1 with 21 zeros following it? So that you have the number:

1,000,000,000,000,000,000,000

or 1x1021

That number could be referred to as one sextillion.

RESPONSE TO ABOVE:

If you live in North America yes the number would be called one sextillion. In almost all other countries however, the number would be called: "one thousand trillion"

This comes from the principle that bi means double or two, and tri means triple or three and hence 1 000 000 = one million

1 000 000 000 000 = one billion ( a bi-million, or double million)

1 000 000 000 000 000 000 = one trillion ( a tri-million, or triple million)

1 000 000 000 000 000 000 000 = one thousand trillion

The safest way to express large numbers when going international is to use powers of ten, 1 x 1021. enjoy!