3
3 is the second prime number and the smallest triangular number greater than 1.
Where 3 fits
Why 3 is special
3 is mathematically notable: 3 has exactly two positive divisors: 1 and itself.
3 in Numbers Around Us
3 is part of
Factors & digit properties
- Divisors (2)
- 1, 3
- Prime factorisation
- 3
- Digit sum
- 3
- Digital root
- 3
Representations
- Decimal
- 3
- Binary
- 11
- Octal
- 3
- Hexadecimal
- 3
- Roman numeral
- III
- Scientific notation
- 3.000 × 10^0
Other mathematical patterns
- Triangular number
- Palindromic number
- Deficient number
- Narcissistic (Armstrong) number
- Harshad (Niven) number
- Lucas number
- Lucky number (mathematical sieve)
- Mersenne prime
- Sophie Germain prime
- Twin prime
Related numbers & connections
27 is the cube of 3 (3³ = 27).
View 27 →3 is the atomic number of lithium.
The RGB colour model combines exactly three channels: red, green, and blue.
Mathematically related
- is the cube of27
why?
Strength 0.50, confidence "high".
Scientific association
- has scientific association withLithium (chemical element)
why?
Strength 0.50, confidence "high".
Numbers Around Us
- appears inRGB colour model
why?
Strength 0.50, confidence "high".
- appears inPhyllotaxis petal patterns
why?
Strength 0.50, confidence "high".
- appears inAspect ratio standards
why?
Strength 0.50, confidence "high".
- appears inMusical time signatures
why?
Strength 0.50, confidence "high".
Science
3 is the atomic number of lithium, the lightest metal, used widely in rechargeable batteries.
DocumentedScience3 is the atomic number of lithium, the lightest metal, used widely in rechargeable batteries.
DocumentedScience
Common questions
Is 3 a prime number?
Yes, 3 is prime — it has exactly two positive divisors: 1 and itself.
What are the factors of 3?
The factors of 3 are 1, 3.
What is 3 in Roman numerals?
3 in Roman numerals is III.
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