1604
Kepler's supernova of 1604 is the last one seen in our galaxy with the naked eye.
- Even
- Composite
Where 1604 fits
Why 1604 is special
Four centuries have passed without another, though the expected rate is roughly one or two per century. Modern surveys find supernovae in other galaxies weekly, which makes the absence in our own a matter of luck and dust rather than of rarity.
Factors & digit properties
- Divisors (6)
- 1, 2, 4, 401, 802, 1604
- Prime factorisation
- 2^2 × 401
- Digit sum
- 11
- Digital root
- 2
Representations
- Decimal
- 1604
- Binary
- 11001000100
- Octal
- 3104
- Hexadecimal
- 644
- Roman numeral
- MDCIV
- Scientific notation
- 1.604 × 10^3
Other mathematical patterns
- Deficient number
Related numbers & connections
Kepler's supernova in 1604 and Galileo's telescope observations in 1610. Between them they removed the idea that the heavens were unchanging and that everything orbited the Earth.
View 1610 →Science
The last naked-eye supernova in the Milky Way was seen in 1604, and the expected rate is one or two a century. The gap is attributed to dust obscuring the galactic plane rather than to supernovae having stopped, but it remains unexplained in any satisfying way.
DocumentedSciencePeriod: 1604
Common questions
Is 1604 a prime number?
No, 1604 is not prime.
What are the factors of 1604?
The factors of 1604 are 1, 2, 4, 401, 802, 1604.
What is 1604 in Roman numerals?
1604 in Roman numerals is MDCIV.
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