261
+261 is the international calling code for Madagascar.
- Odd
- Composite
Where 261 fits
Why 261 is special
Madagascar separated from other landmasses long enough ago that most of its species exist nowhere else. Its people are descended substantially from Austronesian voyagers who crossed the Indian Ocean.
Factors & digit properties
- Divisors (6)
- 1, 3, 9, 29, 87, 261
- Prime factorisation
- 3^2 × 29
- Digit sum
- 9
- Digital root
- 9
Representations
- Decimal
- 261
- Scientific notation
- 2.610 × 10^2
Roman numerals
C C L X I
Binary
1 0 0 0 0 0 1 0 1
1 × 256 + 0 × 128 + 0 × 64 + 0 × 32 + 0 × 16 + 0 × 8 + 1 × 4 + 0 × 2 + 1 × 1 = 261
Octal
4 0 5
4 × 64 + 0 × 8 + 5 × 1 = 261
Hexadecimal
1 0 5
1 × 256 + 0 × 16 + 5 × 1 = 261
Read as powers of two: 256 + 4 + 1 = 261.
In historical numeral systems
Egyptian
2 coils of rope, 6 hobbles, 1 stroke
2 × 100 + 6 × 10 + 1 × 1 = 261. 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), 2 corner wedges + 1 vertical wedge (units place)
4 × 60 + 21 = 261. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
sigma, then xi, then alpha, marked as a numeral
sigma-xi-alpha + keraia
sigma + xi + 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 samekh, then alef
resh-samekh-alef
resh (200) + samekh (60) + alef (1) = 261, written in descending order.
Maya
2 bars + 3 dots (upper, twenties place) over 1 dot (lower, units place)
13 × 20 + 1 = 261. 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
- Harshad (Niven) number
- Lucky number (mathematical sieve)
Related numbers & connections
Seychelles and Madagascar are both Indian Ocean island states with very high proportions of endemic species.
View 248 →Other connections
- is associated with248
why?
Strength 0.50, confidence "high".
Geography
+261 reaches Madagascar, where roughly 90 percent of wildlife is endemic and the population's origins lie substantially in Borneo, several thousand kilometres east.
DocumentedGeographyGeography: Madagascar
Common questions
Is 261 a prime number?
No, 261 is not prime.
What are the factors of 261?
The factors of 261 are 1, 3, 9, 29, 87, 261.
What is 261 in Roman numerals?
261 in Roman numerals is CCLXI.
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