281
NGC 281 is the Pacman Nebula.
- Odd
- Prime
Where 281 fits
Why 281 is special
Its dark lane produces the resemblance, and the informal name is now used in professional literature, which is unusual for a nickname of that origin.
281 is part of
Factors & digit properties
- Divisors (2)
- 1, 281
- Prime factorisation
- 281
- Digit sum
- 11
- Digital root
- 2
Representations
- Decimal
- 281
- Binary
- 100011001
- Octal
- 431
- Hexadecimal
- 119
- Roman numeral
- CCLXXXI
- Scientific notation
- 2.810 × 10^2
Other mathematical patterns
- Deficient number
- Sophie Germain prime
- Twin prime
Related numbers & connections
Both are emission nebulae with young clusters whose radiation will disperse them within a few million years.
View 7380 →Other connections
- is associated with7380
why?
Strength 0.50, confidence "high".
Science
NGC 281 is an emission nebula in Cassiopeia whose foreground dust lane produces its common name, now used alongside the catalogue designation.
DocumentedSciencePeriod: 1883–
Common questions
Is 281 a prime number?
Yes, 281 is prime — it has exactly two positive divisors: 1 and itself.
What are the factors of 281?
The factors of 281 are 1, 281.
What is 281 in Roman numerals?
281 in Roman numerals is CCLXXXI.
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