noun
21st century
Refers to the century from 2001 to 2100.
２１世紀は情報化社会だと言われている。
The 21st century is said to be an information society.
Kanji numeral spelling, common in formal or vertical writing.
Compound of 二十一 (にじゅういち, 'twenty-one') + 世紀 (せいき, 'century').