291
+291 is the international calling code for Eritrea.
- Odd
- Composite
Where 291 fits
Why 291 is special
Eritrea has among the lowest rates of internet access in the world and no privately owned press.
291 is part of
Factors & digit properties
- Divisors (4)
- 1, 3, 97, 291
- Prime factorisation
- 3 × 97
- Digit sum
- 12
- Digital root
- 3
Representations
- Decimal
- 291
- Scientific notation
- 2.910 × 10^2
Roman numerals
C C X C I
CCXCI uses the subtractive pair XC: ten before a hundred — a hundred minus ten.
Binary
1 0 0 1 0 0 0 1 1
1 × 256 + 0 × 128 + 0 × 64 + 1 × 32 + 0 × 16 + 0 × 8 + 0 × 4 + 1 × 2 + 1 × 1 = 291
Octal
4 4 3
4 × 64 + 4 × 8 + 3 × 1 = 291
Hexadecimal
1 2 3
1 × 256 + 2 × 16 + 3 × 1 = 291
Read as powers of two: 256 + 32 + 2 + 1 = 291.
In historical numeral systems
Egyptian
2 coils of rope, 9 hobbles, 1 stroke
2 × 100 + 9 × 10 + 1 × 1 = 291. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
4 vertical wedges (sixties place), 5 corner wedges + 1 vertical wedge (units place)
4 × 60 + 51 = 291. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
sigma, then koppa, then alpha, marked as a numeral
sigma-koppa-alpha + keraia
sigma + koppa + alpha written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
resh, then tsadi, then alef
resh-tsadi-alef
resh (200) + tsadi (90) + alef (1) = 291, written in descending order.
Maya
2 bars + 4 dots (upper, twenties place) over 2 bars + 1 dot (lower, units place)
14 × 20 + 11 = 291. Places stack vertically with the smallest at the bottom, so the upper group is worth twenty times the lower.
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
- Happy number
- Semiprime
Related numbers & connections
Eritrea separated from Ethiopia in 1993 after a thirty-year war. Eritrea has among the lowest internet penetration in the world, which is state policy rather than infrastructure.
View 251 →Nearby in a sequence
- is adjacent to251
why?
Strength 0.50, confidence "high".
Geography
+291 reaches Eritrea, which has one of the world's lowest internet penetration rates and no independent media, both of which are matters of state policy rather than infrastructure.
DocumentedGeographyGeography: Eritrea
Common questions
Is 291 a prime number?
No, 291 is not prime.
What are the factors of 291?
The factors of 291 are 1, 3, 97, 291.
What is 291 in Roman numerals?
291 in Roman numerals is CCXCI. XC is subtractive: ten before a hundred — a hundred minus ten. Written additively it would be CCLXXXXI, 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