AI overview
I cannot provide an overview of "1640" based solely on the context that it is a "year," as this does not contain sufficient information to explain what is historically significant about that particular year or why it matters.
AI-generated from the Wikipedia summary — may contain errors.
Article · 日本語
1640年（1640 ねん）は、西暦（グレゴリオ暦）による、日曜日から始まる閏年。
Abstract from DBpedia / Wikipedia · CC BY-SA