1145
1145 is a year in the 12th century. Eugene III called the Second Crusade after the fall of Edessa (Europe).
- Odd
- Composite
Where 1145 fits
Why 1145 is special
1145 has a profile because of what happened in it rather than because of any property of the number: Eugene III called the Second Crusade after the fall of Edessa (Europe).
1145 is part of
Factors & digit properties
- Divisors (4)
- 1, 5, 229, 1145
- Prime factorisation
- 5 × 229
- Digit sum
- 11
- Digital root
- 2
Representations
- Decimal
- 1145
- Scientific notation
- 1.145 × 10^3
Roman numerals
M C X L V
MCXLV uses the subtractive pair XL: ten before fifty — fifty minus ten.
Binary
1 0 0 0 1 1 1 1 0 0 1
1 × 1,024 + 0 × 512 + 0 × 256 + 0 × 128 + 1 × 64 + 1 × 32 + 1 × 16 + 1 × 8 + 0 × 4 + 0 × 2 + 1 × 1 = 1,145
Octal
2 1 7 1
2 × 512 + 1 × 64 + 7 × 8 + 1 × 1 = 1,145
Hexadecimal
4 7 9
4 × 256 + 7 × 16 + 9 × 1 = 1,145
Read as powers of two: 1,024 + 64 + 32 + 16 + 8 + 1 = 1,145.
In historical numeral systems
Egyptian
1 lotus, 1 coil of rope, 4 hobbles, 5 strokes
1 × 1,000 + 1 × 100 + 4 × 10 + 5 × 1 = 1,145. 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 vertical wedges (units place)
19 × 60 + 5 = 1145. 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
1145 is a year in the 12th century, in the 1140s.
Numbers Around Us
- appears inHistorical years
why?
Strength 0.50, confidence "high".
History
In 1145, Eugene III called the Second Crusade after the fall of Edessa (Europe).
DocumentedHistoryGeography: EuropePeriod: 1145
Common questions
Is 1145 a prime number?
No, 1145 is not prime.
What are the factors of 1145?
The factors of 1145 are 1, 5, 229, 1145.
What is 1145 in Roman numerals?
1145 in Roman numerals is MCXLV. XL is subtractive: ten before fifty — fifty minus ten. Written additively it would be MCXXXXV, 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: 1 reviewer-confirmed record, sourced and reviewed before publication.
Last reviewed: 15 July 2026