1191
1191 is the year Richard I captured Acre on the Third Crusade.
- Odd
- Composite
Where 1191 fits
Why 1191 is special
He spent about six months of a ten-year reign in England and is nonetheless among the most recognised English kings, largely through later legend.
1191 is part of
Factors & digit properties
- Divisors (4)
- 1, 3, 397, 1191
- Prime factorisation
- 3 × 397
- Digit sum
- 12
- Digital root
- 3
Representations
- Decimal
- 1191
- Scientific notation
- 1.191 × 10^3
Roman numerals
M C X C I
MCXCI uses the subtractive pair XC: ten before a hundred — a hundred minus ten.
Binary
1 0 0 1 0 1 0 0 1 1 1
1 × 1,024 + 0 × 512 + 0 × 256 + 1 × 128 + 0 × 64 + 1 × 32 + 0 × 16 + 0 × 8 + 1 × 4 + 1 × 2 + 1 × 1 = 1,191
Octal
2 2 4 7
2 × 512 + 2 × 64 + 4 × 8 + 7 × 1 = 1,191
Hexadecimal
4 a 7
4 × 256 + a × 16 + 7 × 1 = 1,191
Read as powers of two: 1,024 + 128 + 32 + 4 + 2 + 1 = 1,191.
In historical numeral systems
Egyptian
1 lotus, 1 coil of rope, 9 hobbles, 1 stroke
1 × 1,000 + 1 × 100 + 9 × 10 + 1 × 1 = 1,191. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
1 corner wedge + 9 vertical wedges (sixties place), 5 corner wedges + 1 vertical wedge (units place)
19 × 60 + 51 = 1191. 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
- Semiprime
Related numbers & connections
1191 is a year in the 12th century, in the 1190s.
Richard I took Acre in 1191 on the Third Crusade, called after Saladin retook Jerusalem in 1187.
View 1187 →Numbers Around Us
- appears inHistorical years
why?
Strength 0.50, confidence "high".
Other connections
- is associated with1187
why?
Strength 0.50, confidence "high".
History
In 1191, Acre was recaptured after a two-year siege (Levant).
DocumentedHistoryGeography: LevantPeriod: 1191Richard I spent roughly half a year of a ten-year reign in England, speaking little or no English. His prominence in English memory is almost entirely a construction of later storytelling.
DocumentedHistoryGeography: England and the LevantPeriod: 1191
Common questions
Is 1191 a prime number?
No, 1191 is not prime.
What are the factors of 1191?
The factors of 1191 are 1, 3, 397, 1191.
What is 1191 in Roman numerals?
1191 in Roman numerals is MCXCI. XC is subtractive: ten before a hundred — a hundred minus ten. Written additively it would be MCLXXXXI, which Roman inscriptions used freely — the strict subtractive form is a later convention.
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