869
NGC 869 is one half of the Double Cluster in Perseus.
- Odd
- Composite
Where 869 fits
Why 869 is special
It and NGC 884 are genuinely near each other in space rather than merely aligned, which is unusual for a pair that looks like a coincidence.
Factors & digit properties
- Divisors (4)
- 1, 11, 79, 869
- Prime factorisation
- 11 × 79
- Digit sum
- 23
- Digital root
- 5
Representations
- Decimal
- 869
- Binary
- 1101100101
- Octal
- 1545
- Hexadecimal
- 365
- Roman numeral
- DCCCLXIX
- Scientific notation
- 8.690 × 10^2
Other mathematical patterns
- Deficient number
- Semiprime
Related numbers & connections
The Double Cluster is a genuine physical pair at the same distance rather than a line-of-sight coincidence.
View 884 →Numbers Around Us
- appears alongside884
why?
Strength 0.50, confidence "high".
Science
NGC 869 and NGC 884 are open clusters of similar age and distance in the Perseus arm, forming a physically associated pair rather than a chance superposition.
DocumentedSciencePeriod: antiquity–
Common questions
Is 869 a prime number?
No, 869 is not prime.
What are the factors of 869?
The factors of 869 are 1, 11, 79, 869.
What is 869 in Roman numerals?
869 in Roman numerals is DCCCLXIX.
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