United Kingdom vs one million million million

United Kingdom and one million million million both are nouns.

Word	Noun	Adjective	Verb	Adverb
United Kingdom	Yes	No	No	No
one million million million	Yes	No	No	No

United Kingdom (noun)	one million million million (noun)
a monarchy in northwestern Europe occupying most of the British Isles; divided into England and Scotland and Wales and Northern Ireland; `Great Britain' is often used loosely to refer to the United Kingdom	the number that is represented as a one followed by 18 zeros in the UK