36
36 is one of only two numbers below 100 that are both a perfect square (6²) and a triangular number, and the smallest number with exactly nine divisors. A European roulette wheel is numbered 1 to 36.
Where 36 fits
Why 36 is special
36 is one of the few numbers under 100 that is both a perfect square and triangular — and it's the highest number on a standard European roulette wheel.
Same number, different meanings
How 36 is understood across different contexts — never implying one meaning because of another.
- Mathematics
36 is one of the few numbers under 100 that is both a perfect square and triangular — and it's the highest number on a standard European roulette wheel.
- Technology & computing
The lowest channel number in the 5 gigahertz Wi-Fi band is 36 (worldwide, IEEE 802.11). 5 GHz channels are numbered from 36 upward in steps of four, because the numbering counts 5 MHz increments from a base frequency while the channels themselves are 20 MHz apart. Which of them are legal depends on the country and on radar-avoidance rules.
- Media & popular culture
A European roulette wheel and table are numbered 1 to 36 (plus a single zero), making 36 the highest number in the game's standard numbered layout.
- Science
36 is the atomic number of krypton, a noble gas used in some specialised lighting.
Factors & digit properties
- Divisors (9)
- 1, 2, 3, 4, 6, 9, 12, 18, 36
- Prime factorisation
- 2^2 × 3^2
- Digit sum
- 9
- Digital root
- 9
Representations
- Decimal
- 36
- Scientific notation
- 3.600 × 10^1
Roman numerals
X X X V I
Binary
1 0 0 1 0 0
1 × 32 + 0 × 16 + 0 × 8 + 1 × 4 + 0 × 2 + 0 × 1 = 36
Octal
4 4
4 × 8 + 4 × 1 = 36
Hexadecimal
2 4
2 × 16 + 4 × 1 = 36
Read as powers of two: 32 + 4 = 36.
In historical numeral systems
Egyptian
3 hobbles, 6 strokes
3 × 10 + 6 × 1 = 36. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
3 corner wedges + 6 vertical wedges
36 fits in a single sexagesimal place: 3 corner wedges + 6 vertical wedges.
Greek (Ionic)
lambda, then stigma, marked as a numeral
lambda-stigma + keraia
lambda + stigma written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
lamed, then vav
lamed-vav
lamed (30) + vav (6) = 36, written in descending order.
Chinese numerals
sān shí liù
sān shí liù
三 before 十 multiplies it: 3 tens. 六 after it adds 6. The written form mirrors the arithmetic — "sān shí liù". The financial (anti-fraud) form is 參拾陸.
Maya
1 dot (upper, twenties place) over 3 bars + 1 dot (lower, units place)
1 × 20 + 16 = 36. 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
- Triangular number
- Abundant number
- Powerful number
- Highly composite number
- Harshad (Niven) number
Related numbers & connections
36 is a factor of 72 (36 × 2 = 72).
View 72 →36 is the atomic number of krypton.
36 appears in Numbers in radio and communications, the topic covering numbers that carry a documented radio or communications fact.
Mathematically related
- is a factor of72
why?
Strength 0.50, confidence "high".
Scientific association
- has scientific association withKrypton (chemical element)
why?
Strength 0.50, confidence "high".
Numbers Around Us
- appears inRadio and communications
why?
Strength 0.50, confidence "high".
- appears inTransport
why?
Strength 0.50, confidence "high".
Technology & computing
The lowest channel number in the 5 gigahertz Wi-Fi band is 36 (worldwide, IEEE 802.11). 5 GHz channels are numbered from 36 upward in steps of four, because the numbering counts 5 MHz increments from a base frequency while the channels themselves are 20 MHz apart. Which of them are legal depends on the country and on radar-avoidance rules.
DocumentedTechnology & computingGeography: worldwide, IEEE 802.11The highest number a runway can be given is 36 (worldwide, ICAO). Runways are numbered by magnetic heading in tens of degrees, so 36 is due north and there is no runway 37. The same strip carries two numbers 18 apart, one at each end.
DocumentedTechnology & computingGeography: worldwide, ICAOThe altitude of a geostationary orbit is about 36 thousand kilometres. 35,786 kilometres, the one altitude where an orbit takes exactly one day, so the satellite appears to hang still. It is also why a satellite phone call has a noticeable delay: the signal travels 72,000 kilometres.
DocumentedTechnology & computingGeography: worldwideASTM A36 is a carbon structural steel with a specified minimum yield of 36,000 pounds per square inch, from which the designation derives. It is the default grade for structural shapes and plate.
DocumentedTechnology & computingGeography: United States, referenced internationally
Mathematics
Below 100, only 1 and 36 are both square and triangular — 36 is 6² and also 1 + 2 + … + 8. It is additionally the smallest number with exactly nine divisors (1, 2, 3, 4, 6, 9, 12, 18, 36), which is why a 36-item grid divides so many ways.
DocumentedMathematics
Media & popular culture
A European roulette wheel and table are numbered 1 to 36 (plus a single zero), making 36 the highest number in the game's standard numbered layout.
DocumentedMedia & popular culture
Science
36 is the atomic number of krypton, a noble gas used in some specialised lighting.
DocumentedScience
Common questions
Why does a roulette wheel stop at 36?
Because 36 numbers plus a zero gives the house its edge. A winning single-number bet pays 35 to 1, which would be exactly fair on 36 numbers; the zero is the extra pocket that makes it not fair. European wheels have one zero and American wheels two, which is why the American game is the worse bet.
Is 36 the only square that is also triangular?
Below 100, only 1 and 36 are both. They do not stop there — 1,225 and 41,616 are the next two — but they thin out fast, which is what makes 36 the one people meet.
Is 36 a prime number?
No, 36 is not prime.
What are the factors of 36?
The factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18, 36.
What is 36 in Roman numerals?
36 in Roman numerals is XXXVI.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 7 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026