525
K. 525 is Eine kleine Nachtmusik.
- Odd
- Composite
Where 525 fits
Why 525 is special
The catalogue records five movements and only four survive, so one of the most played pieces in the repertoire is incomplete.
Factors & digit properties
- Divisors (12)
- 1, 3, 5, 7, 15, 21, 25, 35, 75, 105, 175, 525
- Prime factorisation
- 3 × 5^2 × 7
- Digit sum
- 12
- Digital root
- 3
Representations
- Decimal
- 525
- Scientific notation
- 5.250 × 10^2
Roman numerals
D X X V
Binary
1 0 0 0 0 0 1 1 0 1
1 × 512 + 0 × 256 + 0 × 128 + 0 × 64 + 0 × 32 + 0 × 16 + 1 × 8 + 1 × 4 + 0 × 2 + 1 × 1 = 525
Octal
1 0 1 5
1 × 512 + 0 × 64 + 1 × 8 + 5 × 1 = 525
Hexadecimal
2 0 d
2 × 256 + 0 × 16 + d × 1 = 525
Read as powers of two: 512 + 8 + 4 + 1 = 525.
In historical numeral systems
Egyptian
5 coils of rope, 2 hobbles, 5 strokes
5 × 100 + 2 × 10 + 5 × 1 = 525. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
8 vertical wedges (sixties place), 4 corner wedges + 5 vertical wedges (units place)
8 × 60 + 45 = 525. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
phi, then kappa, then epsilon, marked as a numeral
phi-kappa-epsilon + keraia
phi + kappa + epsilon written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
tav, then qof, then kaf, then he
tav-qof-kaf-he
tav (400) + qof (100) + kaf (20) + he (5) = 525, written in descending order.
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
- Palindromic number
- Deficient number
Related numbers & connections
K. 525 is a Köchel catalogue number, the identifier by which Mozart's works are cited in every programme note.
A 2014 manuscript find changed a very familiar piece, as the missing movement leaves another incomplete.
View 331 →Media & popular culture
K. 525 is listed in Mozart's own catalogue with five movements. The minuet and trio that stood second is lost, so the work is performed in four movements.
DocumentedMedia & popular cultureGeography: AustriaPeriod: 1787
Common questions
Is 525 a prime number?
No, 525 is not prime.
What are the factors of 525?
The factors of 525 are 1, 3, 5, 7, 15, 21, 25, 35, 75, 105, 175, 525.
What is 525 in Roman numerals?
525 in Roman numerals is DXXV.
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: 15 July 2026