841
A0 paper is 841 mm wide.
Where 841 fits
Why 841 is special
A0 is defined as one square metre with sides in the ratio of the square root of two, which works out to 841 by 1,189 mm. Every other A size is that sheet halved a number of times, so the whole series follows from a square metre.
841 is part of
Factors & digit properties
- Divisors (3)
- 1, 29, 841
- Prime factorisation
- 29^2
- Digit sum
- 13
- Digital root
- 4
Representations
- Decimal
- 841
- Scientific notation
- 8.410 × 10^2
Roman numerals
D C C C X L I
DCCCXLI uses the subtractive pair XL: ten before fifty — fifty minus ten.
Binary
1 1 0 1 0 0 1 0 0 1
1 × 512 + 1 × 256 + 0 × 128 + 1 × 64 + 0 × 32 + 0 × 16 + 1 × 8 + 0 × 4 + 0 × 2 + 1 × 1 = 841
Octal
1 5 1 1
1 × 512 + 5 × 64 + 1 × 8 + 1 × 1 = 841
Hexadecimal
3 4 9
3 × 256 + 4 × 16 + 9 × 1 = 841
Read as powers of two: 512 + 256 + 64 + 8 + 1 = 841.
In historical numeral systems
Egyptian
8 coils of rope, 4 hobbles, 1 stroke
8 × 100 + 4 × 10 + 1 × 1 = 841. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
1 corner wedge + 4 vertical wedges (sixties place), 1 vertical wedge (units place)
14 × 60 + 1 = 841. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
omega, then mu, then alpha, marked as a numeral
omega-mu-alpha + keraia
omega + mu + alpha 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 tav, then mem, then alef
tav-tav-mem-alef
tav (400) + tav (400) + mem (40) + alef (1) = 841, 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
- Deficient number
- Powerful number
- Semiprime
- Lucky number (mathematical sieve)
Related numbers & connections
A1 is 594 by 841 mm and A0 is 841 by 1,189. The chain from A0 down to A5 is five halvings of a single square metre.
View 594 →841 by 1,189 mm is one square metre with sides in the square-root-of-two ratio, which is the definition every other A size is derived from.
View 1189 →Everyday life
A0 is 841 by 1,189 mm — one square metre, with sides in the square-root-of-two ratio. A4 is that sheet halved four times, which is why an A4 sheet is exactly one sixteenth of a square metre and why paper weight is quoted in grams per square metre.
DocumentedEveryday lifeGeography: International outside North America
Common questions
Is 841 a prime number?
No, 841 is not prime.
What are the factors of 841?
The factors of 841 are 1, 29, 841.
What is 841 in Roman numerals?
841 in Roman numerals is DCCCXLI. XL is subtractive: ten before fifty — fifty minus ten. Written additively it would be DCCCXXXXI, 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: 1 reviewer-confirmed record, sourced and reviewed before publication.
Last reviewed: 15 July 2026