1,609
1609 is the rounded number of metres in a statute mile. The exact figure is 1609.344 metres.
- Odd
- Prime
Where 1,609 fits
Why 1,609 is special
1609 is a rounding, and saying so is the point: the statute mile is defined as exactly 1609.344 metres, a figure fixed by the 1959 international yard and pound agreement rather than measured. It sits alongside 5280 — the same mile counted in feet — as the two numbers you get from measuring one distance in two systems, and it contrasts directly with the kilometre's deliberately round 1000 metres. Unrelated to any of that, 1609 is prime.
Same number, different meanings
How 1,609 is understood across different contexts — never implying one meaning because of another.
- Mathematics
1609 is a rounding, and saying so is the point: the statute mile is defined as exactly 1609.344 metres, a figure fixed by the 1959 international yard and pound agreement rather than measured. It sits alongside 5280 — the same mile counted in feet — as the two numbers you get from measuring one distance in two systems, and it contrasts directly with the kilometre's deliberately round 1000 metres. Unrelated to any of that, 1609 is prime.
- History
The mile's exact metric length was fixed by the 1959 international yard and pound agreement, which defined the international yard as exactly 0.9144 metres. Every imperial length below the mile follows from that single definition.
- Science
In 1609, Galileo turned a telescope on the night sky, and Kepler published his first two laws of planetary motion (Europe).
- Everyday life
One statute mile is exactly 1609.344 metres. 1609 is the rounded integer commonly used in conversions, but the defined value carries three decimal places and is exact rather than measured.
1,609 is part of
Factors & digit properties
- Divisors (2)
- 1, 1609
- Prime factorisation
- 1609
- Digit sum
- 16
- Digital root
- 7
Representations
- Decimal
- 1609
- Scientific notation
- 1.609 × 10^3
Roman numerals
M D C I X
MDCIX uses the subtractive pair IX: one before ten — ten minus one.
Binary
1 1 0 0 1 0 0 1 0 0 1
1 × 1,024 + 1 × 512 + 0 × 256 + 0 × 128 + 1 × 64 + 0 × 32 + 0 × 16 + 1 × 8 + 0 × 4 + 0 × 2 + 1 × 1 = 1,609
Octal
3 1 1 1
3 × 512 + 1 × 64 + 1 × 8 + 1 × 1 = 1,609
Hexadecimal
6 4 9
6 × 256 + 4 × 16 + 9 × 1 = 1,609
Read as powers of two: 1,024 + 512 + 64 + 8 + 1 = 1,609.
In historical numeral systems
Egyptian
1 lotus, 6 coils of rope, 9 strokes
1 × 1,000 + 6 × 100 + 9 × 1 = 1,609. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
2 corner wedges + 6 vertical wedges (sixties place), 4 corner wedges + 9 vertical wedges (units place)
26 × 60 + 49 = 1609. Places are separated by a space on the tablet, with the higher place written first.
Systems that simply cannot reach this value are left out. Where a script needs a font most readers do not have, the reading is given instead of the glyphs — see number systems for each system in full.
Other mathematical patterns
- Deficient number
- Twin prime
Related numbers & connections
1609 is a year in the 17th century, in the 1600s.
1609 metres and 5280 feet are the same statute mile measured in two systems — the metric figure is exact at 1609.344 m by definition, the imperial one exact at 5280 ft by the mile's 1760-yard construction.
View 5280 →Numbers Around Us
- appears inHistorical years
why?
Strength 0.50, confidence "high".
History
The mile's exact metric length was fixed by the 1959 international yard and pound agreement, which defined the international yard as exactly 0.9144 metres. Every imperial length below the mile follows from that single definition.
DocumentedHistoryGeography: United States, United Kingdom, Canada, Australia, New Zealand, South AfricaPeriod: 1959
Science
In 1609, Galileo turned a telescope on the night sky, and Kepler published his first two laws of planetary motion (Europe).
DocumentedScienceGeography: EuropePeriod: 1609Kepler found that Mars's orbit could not be reconciled with circles at any level of complexity, and concluded it was an ellipse. Discarding circular motion was a larger break than moving the Sun to the centre.
DocumentedSciencePeriod: 1609
Everyday life
One statute mile is exactly 1609.344 metres. 1609 is the rounded integer commonly used in conversions, but the defined value carries three decimal places and is exact rather than measured.
DocumentedEveryday lifeGeography: imperial and US customary units
Mathematics
1609 is a prime number. This is unrelated to its role in measurement — the mile's metric length happening to round to a prime is a coincidence, not a property of the definition.
DocumentedMathematics
Common questions
Is 1,609 a prime number?
Yes, 1,609 is prime — it has exactly two positive divisors: 1 and itself.
What are the factors of 1,609?
The factors of 1,609 are 1, 1609.
What is 1,609 in Roman numerals?
1,609 in Roman numerals is MDCIX. IX is subtractive: one before ten — ten minus one. Written additively it would be MDCVIIII, which Roman inscriptions used freely — the strict subtractive form is a later convention.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 5 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026