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
- Binary
- 100000101
- Octal
- 405
- Hexadecimal
- 105
- Roman numeral
- CCLXI
- Scientific notation
- 2.610 × 10^2
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: 3 August 2026