331
K. 331 ends with the Rondo alla Turca.
- Odd
- Prime
Where 331 fits
Why 331 is special
A manuscript found in Budapest in 2014 differs from the printed text that had been played for two centuries, changing notes in a very familiar piece.
331 connects to:
- numbers in physics — appears in
- 525 — is associated with
Same number, different meanings
How 331 is understood across different contexts — never implying one meaning because of another.
- Mathematics
A manuscript found in Budapest in 2014 differs from the printed text that had been played for two centuries, changing notes in a very familiar piece.
- Science
The speed of sound in dry air at freezing point is 331 metres per second (worldwide, dry air at 0 degrees Celsius). Sound travels faster in warmer air, gaining roughly 0.6 metres per second per degree — so the familiar 343 figure is this number plus twenty degrees of warming.
- Media & popular culture
K. 331 is the piano sonata whose finale is the Rondo alla Turca. A partial autograph identified in Budapest in 2014 shows readings differing from the previously accepted edition.
331 is part of
Factors & digit properties
- Divisors (2)
- 1, 331
- Prime factorisation
- 331
- Digit sum
- 7
- Digital root
- 7
Representations
- Decimal
- 331
- Scientific notation
- 3.310 × 10^2
Roman numerals
C C C X X X I
Binary
1 0 1 0 0 1 0 1 1
1 × 256 + 0 × 128 + 1 × 64 + 0 × 32 + 0 × 16 + 1 × 8 + 0 × 4 + 1 × 2 + 1 × 1 = 331
Octal
5 1 3
5 × 64 + 1 × 8 + 3 × 1 = 331
Hexadecimal
1 4 b
1 × 256 + 4 × 16 + b × 1 = 331
Read as powers of two: 256 + 64 + 8 + 2 + 1 = 331.
In historical numeral systems
Egyptian
3 coils of rope, 3 hobbles, 1 stroke
3 × 100 + 3 × 10 + 1 × 1 = 331. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
5 vertical wedges (sixties place), 3 corner wedges + 1 vertical wedge (units place)
5 × 60 + 31 = 331. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
tau, then lambda, then alpha, marked as a numeral
tau-lambda-alpha + keraia
tau + lambda + alpha written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
shin, then lamed, then alef
shin-lamed-alef
shin (300) + lamed (30) + alef (1) = 331, written in descending order.
Maya
3 bars + 1 dot (upper, twenties place) over 2 bars + 1 dot (lower, units place)
16 × 20 + 11 = 331. Places stack vertically with the smallest at the bottom, so the upper group is worth twenty times the lower.
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
- Happy number
- Lucky number (mathematical sieve)
Related numbers & connections
331 appears in Numbers in physics, the topic covering numbers that carry a documented physics fact.
A 2014 manuscript find changed a very familiar piece, as the missing movement leaves another incomplete.
View 525 →Numbers Around Us
- appears inPhysics
why?
Strength 0.50, confidence "high".
Other connections
- is associated with525
why?
Strength 0.50, confidence "high".
Science
The speed of sound in dry air at freezing point is 331 metres per second (worldwide, dry air at 0 degrees Celsius). Sound travels faster in warmer air, gaining roughly 0.6 metres per second per degree — so the familiar 343 figure is this number plus twenty degrees of warming.
DocumentedScienceGeography: worldwide, dry air at 0 degrees Celsius
Media & popular culture
K. 331 is the piano sonata whose finale is the Rondo alla Turca. A partial autograph identified in Budapest in 2014 shows readings differing from the previously accepted edition.
DocumentedMedia & popular cultureGeography: AustriaPeriod: c.1783
Common questions
Is 331 a prime number?
Yes, 331 is prime — it has exactly two positive divisors: 1 and itself.
What are the factors of 331?
The factors of 331 are 1, 331.
What is 331 in Roman numerals?
331 in Roman numerals is CCCXXXI.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 2 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026