1680
1682
The Number 1681: Properties and Meanings
Prime Factors of 1681=41x41.
1681 is a Square Number(41x41).
1681 is a Centered Octagonal Number.
1681 is a Centered 14-gonal Number.
1681 is a Centered 16-gonal Number.
1681 is a square and each of its two 2-digit parts is square.
The Year 1681 AD
In the year 1681 AD William Lilly, astrologer and translator of Trithemius, died.(Esoteric History)
1680
1682