133
E133 is Brilliant Blue FCF.
- Odd
- Composite
Where 133 fits
Why 133 is special
It was banned in several European countries for decades while being permitted in the United States, and the positions later reversed in part.
Same number, different meanings
How 133 is understood across different contexts — never implying one meaning because of another.
- Mathematics
It was banned in several European countries for decades while being permitted in the United States, and the positions later reversed in part.
- Science
The SI second is defined as 9,192,631,770 periods of a specific transition in caesium-133. The definition moved timekeeping off astronomy in 1967, so a second is now fixed by atomic physics rather than by the Earth's rotation.
- Everyday life
E133 Brilliant Blue FCF is a synthetic triarylmethane dye. National bans in several European states preceded EU-wide authorisation, an inversion of the usual pattern with United States approval.
133 is part of
Factors & digit properties
- Divisors (4)
- 1, 7, 19, 133
- Prime factorisation
- 7 × 19
- Digit sum
- 7
- Digital root
- 7
Representations
- Decimal
- 133
- Scientific notation
- 1.330 × 10^2
Roman numerals
C X X X I I I
Binary
1 0 0 0 0 1 0 1
1 × 128 + 0 × 64 + 0 × 32 + 0 × 16 + 0 × 8 + 1 × 4 + 0 × 2 + 1 × 1 = 133
Octal
2 0 5
2 × 64 + 0 × 8 + 5 × 1 = 133
Hexadecimal
8 5
8 × 16 + 5 × 1 = 133
Read as powers of two: 128 + 4 + 1 = 133.
In historical numeral systems
Egyptian
1 coil of rope, 3 hobbles, 3 strokes
1 × 100 + 3 × 10 + 3 × 1 = 133. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
2 vertical wedges (sixties place), 1 corner wedge + 3 vertical wedges (units place)
2 × 60 + 13 = 133. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
rho, then lambda, then gamma, marked as a numeral
rho-lambda-gamma + keraia
rho + lambda + gamma written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
qof, then lamed, then gimel
qof-lamed-gimel
qof (100) + lamed (30) + gimel (3) = 133, written in descending order.
Maya
1 bar + 1 dot (upper, twenties place) over 2 bars + 3 dots (lower, units place)
6 × 20 + 13 = 133. 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
- Semiprime
- Harshad (Niven) number
- Lucky number (mathematical sieve)
Related numbers & connections
The SI second is defined by 9,192,631,770 periods of a transition in caesium-133, which moved timekeeping off astronomy in 1967.
Defining the second by caesium-133 fixed the unit that sixty of them make a minute.
View 60 →Science
The SI second is defined as 9,192,631,770 periods of a specific transition in caesium-133. The definition moved timekeeping off astronomy in 1967, so a second is now fixed by atomic physics rather than by the Earth's rotation.
DocumentedScienceGeography: International — BIPMPeriod: 1967–
Everyday life
E133 Brilliant Blue FCF is a synthetic triarylmethane dye. National bans in several European states preceded EU-wide authorisation, an inversion of the usual pattern with United States approval.
DocumentedEveryday lifeGeography: European Union and states adopting the E number systemPeriod: 1962–
Common questions
Is 133 a prime number?
No, 133 is not prime.
What are the factors of 133?
The factors of 133 are 1, 7, 19, 133.
What is 133 in Roman numerals?
133 in Roman numerals is CXXXIII.
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