1000000 vs one thousand thousand

1000000 and one thousand thousand both are nouns.

Word	Noun	Adjective	Verb	Adverb
1000000	Yes	No	No	No
one thousand thousand	Yes	No	No	No

As nouns, 1000000 and one thousand thousand are synonyms defined as:

1000000 and one thousand thousand: the number that is represented as a one followed by 6 zeros

Other synonyms of 1000000 include meg, million.

1000000 (noun)	one thousand thousand (noun)
the number that is represented as a one followed by 6 zeros	the number that is represented as a one followed by 6 zeros