1261
1261 is a year in the 13th century. Byzantine forces retook Constantinople from the Latin empire (Constantinople).
- Odd
- Composite
Where 1261 fits
Why 1261 is special
1261 has a profile because of what happened in it rather than because of any property of the number: Byzantine forces retook Constantinople from the Latin empire (Constantinople).
1261 is part of
Factors & digit properties
- Divisors (4)
- 1, 13, 97, 1261
- Prime factorisation
- 13 × 97
- Digit sum
- 10
- Digital root
- 1
Representations
- Decimal
- 1261
- Scientific notation
- 1.261 × 10^3
Roman numerals
M C C L X I
Binary
1 0 0 1 1 1 0 1 1 0 1
1 × 1,024 + 0 × 512 + 0 × 256 + 1 × 128 + 1 × 64 + 1 × 32 + 0 × 16 + 1 × 8 + 1 × 4 + 0 × 2 + 1 × 1 = 1,261
Octal
2 3 5 5
2 × 512 + 3 × 64 + 5 × 8 + 5 × 1 = 1,261
Hexadecimal
4 e d
4 × 256 + e × 16 + d × 1 = 1,261
Read as powers of two: 1,024 + 128 + 64 + 32 + 8 + 4 + 1 = 1,261.
In historical numeral systems
Egyptian
1 lotus, 2 coils of rope, 6 hobbles, 1 stroke
1 × 1,000 + 2 × 100 + 6 × 10 + 1 × 1 = 1,261. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
2 corner wedges + 1 vertical wedge (sixties place), 1 vertical wedge (units place)
21 × 60 + 1 = 1261. 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
- Lucky number (mathematical sieve)
Related numbers & connections
1261 is a year in the 13th century, in the 1260s.
Numbers Around Us
- appears inHistorical years
why?
Strength 0.50, confidence "high".
History
In 1261, Byzantine forces retook Constantinople from the Latin empire (Constantinople).
DocumentedHistoryGeography: ConstantinoplePeriod: 1261
Common questions
Is 1261 a prime number?
No, 1261 is not prime.
What are the factors of 1261?
The factors of 1261 are 1, 13, 97, 1261.
What is 1261 in Roman numerals?
1261 in Roman numerals is MCCLXI.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 1 reviewer-confirmed record, sourced and reviewed before publication.
Last reviewed: 15 July 2026