Numberwise

6581

The 6581 is the SID sound chip of the Commodore 64.

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Where 6581 fits

Where 6581 fits: Mathematics, Technology, Related numbersMathematics: Prime, Sophie Germain prime. Technology: Numbers assigned as identifiers. Related numbers: 64, 4066, 2612, 8580.MathematicsPrimeSophie Germain primeTechnologyNumbers assigned as identif…Related numbers644066261285806581
6581 connects to 3 worlds: mathematics, technology, related numbers.

Why 6581 is special

It was designed by a synthesiser engineer rather than a chip specialist, and manufacturing variation gives individual chips audibly different filters — which is why collectors care which one they have.

6581 is part of

Identifier numbersPrime numbersNumbers around us

Factors & digit properties

Divisors (2)
1, 6581
Prime factorisation
6581
Digit sum
20
Digital root
2

Representations

Decimal
6581
Scientific notation
6.581 × 10^3

Roman numerals

Roman numerals as modelled here goes up to 3,999.

Binary

1 1 0 0 1 1 0 1 1 0 1 0 1

1 × 4,096 + 1 × 2,048 + 0 × 1,024 + 0 × 512 + 1 × 256 + 1 × 128 + 0 × 64 + 1 × 32 + 1 × 16 + 0 × 8 + 1 × 4 + 0 × 2 + 1 × 1 = 6,581

Octal

1 4 6 6 5

1 × 4,096 + 4 × 512 + 6 × 64 + 6 × 8 + 5 × 1 = 6,581

Hexadecimal

1 9 b 5

1 × 4,096 + 9 × 256 + b × 16 + 5 × 1 = 6,581

Read as powers of two: 4,096 + 2,048 + 256 + 128 + 32 + 16 + 4 + 1 = 6,581.

In historical numeral systems

Egyptian

6 lotuses, 5 coils of rope, 8 hobbles, 1 stroke

6 × 1,000 + 5 × 100 + 8 × 10 + 1 × 1 = 6,581. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.

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

Related numbers & connections

Documented appearance
The 6581 part number labels the SID sound chip, and enthusiasts distinguish revisions by number alone.

The 6581 part number labels the SID sound chip, and enthusiasts distinguish revisions by number alone.

Connection
The SID gave the Commodore 64 a sound no competitor matched, and manufacturing variation made individual chips audibly different.

The SID gave the Commodore 64 a sound no competitor matched, and manufacturing variation made individual chips audibly different.

View 64 →

Numbers Around Us

  • appears inNumbers assigned as identifiers
    why?

    Strength 0.50, confidence "high".

Other connections

  • is associated with64
    why?

    Strength 0.50, confidence "high".

  • is associated with4066
    why?

    Strength 0.50, confidence "high".

  • contrasts with2612
    why?

    Strength 0.50, confidence "high".

  • developed from8580
    why?

    Strength 0.50, confidence "high".

How is 6581 connected to another number? →

Media & popular culture

  • The 6581 Sound Interface Device provides three oscillators with independent waveforms and a multi-mode analogue filter. Process variation left the filter cutoff inconsistent between chips, giving individual units distinct character.

    DocumentedMedia & popular culturePeriod: 1982–

Common questions

Is 6581 a prime number?

Yes, 6581 is prime — it has exactly two positive divisors: 1 and itself.

What are the factors of 6581?

The factors of 6581 are 1, 6581.

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