Yes, it is!
i heard somewhere that the greatest invention of the 21st century is the internet.
* *
YES!
internet
Perhaps the car, telephone, computer, television, or the iPhone. the car, telephone, computer and the tv arent 21st century or important it would have to be a form of medicine
21st century.
We are in the 21st Century.
It is in the 21st century.
the 21st century
~this is the 21st century
Yes they do have batteries in the 21st century and had in the 20th century.
No, there is no apostrophe in the phrase "21st century."