1681
1681 is the year the dodo was last reliably reported.
Where 1681 fits
Why 1681 is special
Extinction within about a century of European contact made it the standard emblem of human-caused extinction, and 'dead as a dodo' entered the language.
Same number, different meanings
How 1681 is understood across different contexts — never implying one meaning because of another.
- Mathematics
Extinction within about a century of European contact made it the standard emblem of human-caused extinction, and 'dead as a dodo' entered the language.
- History
In 1681, William Penn received the charter for Pennsylvania (North America).
- Science
The dodo disappeared within roughly a century of Europeans reaching Mauritius, mostly through introduced animals eating its eggs rather than direct hunting. The last credible sighting is around 1681.
1681 is part of
Factors & digit properties
- Divisors (3)
- 1, 41, 1681
- Prime factorisation
- 41^2
- Digit sum
- 16
- Digital root
- 7
Representations
- Decimal
- 1681
- Scientific notation
- 1.681 × 10^3
Roman numerals
M D C L X X X I
Binary
1 1 0 1 0 0 1 0 0 0 1
1 × 1,024 + 1 × 512 + 0 × 256 + 1 × 128 + 0 × 64 + 0 × 32 + 1 × 16 + 0 × 8 + 0 × 4 + 0 × 2 + 1 × 1 = 1,681
Octal
3 2 2 1
3 × 512 + 2 × 64 + 2 × 8 + 1 × 1 = 1,681
Hexadecimal
6 9 1
6 × 256 + 9 × 16 + 1 × 1 = 1,681
Read as powers of two: 1,024 + 512 + 128 + 16 + 1 = 1,681.
In historical numeral systems
Egyptian
1 lotus, 6 coils of rope, 8 hobbles, 1 stroke
1 × 1,000 + 6 × 100 + 8 × 10 + 1 × 1 = 1,681. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
2 corner wedges + 8 vertical wedges (sixties place), 1 vertical wedge (units place)
28 × 60 + 1 = 1681. Places are separated by a space on the tablet, with the higher place written first.
Systems that simply cannot reach this value are left out. Where a script needs a font most readers do not have, the reading is given instead of the glyphs — see number systems for each system in full.
Other mathematical patterns
- Deficient number
- Powerful number
- Semiprime
Related numbers & connections
1681 is a year in the 17th century, in the 1680s.
Numbers Around Us
- appears inHistorical years
why?
Strength 0.50, confidence "high".
History
In 1681, William Penn received the charter for Pennsylvania (North America).
DocumentedHistoryGeography: North AmericaPeriod: 1681
Science
The dodo disappeared within roughly a century of Europeans reaching Mauritius, mostly through introduced animals eating its eggs rather than direct hunting. The last credible sighting is around 1681.
DocumentedScienceGeography: MauritiusPeriod: 1681
Common questions
Is 1681 a prime number?
No, 1681 is not prime.
What are the factors of 1681?
The factors of 1681 are 1, 41, 1681.
What is 1681 in Roman numerals?
1681 in Roman numerals is MDCLXXXI.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 2 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026