1231
1231 is the year the papal Inquisition was formally established.
- Odd
- Prime
Where 1231 fits
Why 1231 is special
It was created partly to replace mob violence and secular lynching with a procedure that required evidence and permitted defence. That it became an instrument of terror does not change what it displaced.
Same number, different meanings
How 1231 is understood across different contexts — never implying one meaning because of another.
- Mathematics
It was created partly to replace mob violence and secular lynching with a procedure that required evidence and permitted defence. That it became an instrument of terror does not change what it displaced.
- History
In 1231, the papal Inquisition was established as a standing tribunal (Europe).
- Law & regulation
The medieval Inquisition introduced rules of evidence where accusations had previously led to lynching. Judged against what preceded it the change was real; judged against what it became the point is easily overstated.
1231 is part of
Factors & digit properties
- Divisors (2)
- 1, 1231
- Prime factorisation
- 1231
- Digit sum
- 7
- Digital root
- 7
Representations
- Decimal
- 1231
- Scientific notation
- 1.231 × 10^3
Roman numerals
M C C X X X I
Binary
1 0 0 1 1 0 0 1 1 1 1
1 × 1,024 + 0 × 512 + 0 × 256 + 1 × 128 + 1 × 64 + 0 × 32 + 0 × 16 + 1 × 8 + 1 × 4 + 1 × 2 + 1 × 1 = 1,231
Octal
2 3 1 7
2 × 512 + 3 × 64 + 1 × 8 + 7 × 1 = 1,231
Hexadecimal
4 c f
4 × 256 + c × 16 + f × 1 = 1,231
Read as powers of two: 1,024 + 128 + 64 + 8 + 4 + 2 + 1 = 1,231.
In historical numeral systems
Egyptian
1 lotus, 2 coils of rope, 3 hobbles, 1 stroke
1 × 1,000 + 2 × 100 + 3 × 10 + 1 × 1 = 1,231. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
2 corner wedges (sixties place), 3 corner wedges + 1 vertical wedge (units place)
20 × 60 + 31 = 1231. 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
- Lucky number (mathematical sieve)
- Twin prime
Related numbers & connections
1231 is a year in the 13th century, in the 1230s.
The papal Inquisition of 1231 introduced rules of evidence where lynching had prevailed; the Spanish Inquisition from 1481 answered to the crown rather than to Rome, which is what made it an instrument of state.
View 1481 →Numbers Around Us
- appears inHistorical years
why?
Strength 0.50, confidence "high".
Other connections
- developed from1481
why?
Strength 0.50, confidence "high".
History
In 1231, the papal Inquisition was established as a standing tribunal (Europe).
DocumentedHistoryGeography: EuropePeriod: 1231
Law & regulation
The medieval Inquisition introduced rules of evidence where accusations had previously led to lynching. Judged against what preceded it the change was real; judged against what it became the point is easily overstated.
DocumentedLaw & regulationGeography: EuropePeriod: 1231
Common questions
Is 1231 a prime number?
Yes, 1231 is prime — it has exactly two positive divisors: 1 and itself.
What are the factors of 1231?
The factors of 1231 are 1, 1231.
What is 1231 in Roman numerals?
1231 in Roman numerals is MCCXXXI.
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