553
The CN Tower is 553 metres tall.
- Odd
- Composite
Where 553 fits
Why 553 is special
It held the record for tallest free-standing structure from 1975 to 2007. Its purpose was practical: Toronto's new skyscrapers were blocking broadcast signals, so a taller transmitter was needed.
Factors & digit properties
- Divisors (4)
- 1, 7, 79, 553
- Prime factorisation
- 7 × 79
- Digit sum
- 13
- Digital root
- 4
Representations
- Decimal
- 553
- Scientific notation
- 5.530 × 10^2
Roman numerals
D L I I I
Binary
1 0 0 0 1 0 1 0 0 1
1 × 512 + 0 × 256 + 0 × 128 + 0 × 64 + 1 × 32 + 0 × 16 + 1 × 8 + 0 × 4 + 0 × 2 + 1 × 1 = 553
Octal
1 0 5 1
1 × 512 + 0 × 64 + 5 × 8 + 1 × 1 = 553
Hexadecimal
2 2 9
2 × 256 + 2 × 16 + 9 × 1 = 553
Read as powers of two: 512 + 32 + 8 + 1 = 553.
In historical numeral systems
Egyptian
5 coils of rope, 5 hobbles, 3 strokes
5 × 100 + 5 × 10 + 3 × 1 = 553. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
9 vertical wedges (sixties place), 1 corner wedge + 3 vertical wedges (units place)
9 × 60 + 13 = 553. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
phi, then nu, then gamma, marked as a numeral
phi-nu-gamma + keraia
phi + nu + gamma 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 nun, then gimel
tav-qof-nun-gimel
tav (400) + qof (100) + nun (50) + gimel (3) = 553, 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
- Semiprime
- Lucky number (mathematical sieve)
Related numbers & connections
The Burj Khalifa and the CN Tower held different records — tallest structure and tallest free-standing structure — and the distinction between categories is exactly what makes height records contentious.
View 828 →Other connections
- contrasts with828
why?
Strength 0.50, confidence "high".
Technology & computing
The CN Tower was built in 1975 because downtown skyscrapers were interfering with broadcast reception. A structure that held a world record for 32 years exists to solve a radio-propagation problem.
DocumentedTechnology & computingGeography: Toronto, CanadaPeriod: 1975–2007
Common questions
Is 553 a prime number?
No, 553 is not prime.
What are the factors of 553?
The factors of 553 are 1, 7, 79, 553.
What is 553 in Roman numerals?
553 in Roman numerals is DLIII.
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