63
63 is the atomic number of europium, sitting one below the power of two 64.
- Odd
- Composite
Where 63 fits
Why 63 is special
63 (7 × 9) is best understood by its neighbour: one less than 64, itself both a square and a binary power.
Factors & digit properties
- Divisors (6)
- 1, 3, 7, 9, 21, 63
- Prime factorisation
- 3^2 × 7
- Digit sum
- 9
- Digital root
- 9
Representations
- Decimal
- 63
- Binary
- 111111
- Octal
- 77
- Hexadecimal
- 3f
- Roman numeral
- LXIII
- Scientific notation
- 6.300 × 10^1
Other mathematical patterns
- Deficient number
- Harshad (Niven) number
- Lucky number (mathematical sieve)
Related numbers & connections
Mathematical relationship9 is a factor of 63 (9 × 7 = 63).
63 has factor 99 is a factor of 63 (9 × 7 = 63).
9 is a factor of 63 (9 × 7 = 63).
View 9 →Mathematically related
- has factor9
why?
Strength 0.50, confidence "high".
Science
63 is the atomic number of europium.
DocumentedScience
Mathematics
63 = 7 × 9 = 7 × 3², sitting one below the power of two 64.
DocumentedMathematics
Common questions
Is 63 a prime number?
No, 63 is not prime.
What are the factors of 63?
The factors of 63 are 1, 3, 7, 9, 21, 63.
What is 63 in Roman numerals?
63 in Roman numerals is LXIII.
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