1655
1655 is the year Huygens identified Saturn's rings as a ring.
- Odd
- Composite
Where 1655 fits
Why 1655 is special
Galileo had seen something either side of the planet and could not resolve it, describing Saturn as having ears. Better optics turned a puzzle into a description.
Factors & digit properties
- Divisors (4)
- 1, 5, 331, 1655
- Prime factorisation
- 5 × 331
- Digit sum
- 17
- Digital root
- 8
Representations
- Decimal
- 1655
- Binary
- 11001110111
- Octal
- 3167
- Hexadecimal
- 677
- Roman numeral
- MDCLV
- Scientific notation
- 1.655 × 10^3
Other mathematical patterns
- Deficient number
- Semiprime
Science
Galileo saw protrusions either side of Saturn in 1610 and had no framework for them. Huygens, with a better telescope, established in 1655 that they were a detached ring, which nothing else in the sky resembled.
DocumentedSciencePeriod: 1655
Common questions
Is 1655 a prime number?
No, 1655 is not prime.
What are the factors of 1655?
The factors of 1655 are 1, 5, 331, 1655.
What is 1655 in Roman numerals?
1655 in Roman numerals is MDCLV.
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