66
66 is the atomic number of dysprosium, and the number of the historic US Route 66.
- Even
- Composite
Where 66 fits
Why 66 is special
66's cultural fame comes from Route 66, the storied Chicago-to-Santa-Monica highway (1926-1985) that remains a symbol of mid-20th-century American road culture.
Same number, different meanings
How 66 is understood across different contexts — never implying one meaning because of another.
- Mathematics
66's cultural fame comes from Route 66, the storied Chicago-to-Santa-Monica highway (1926-1985) that remains a symbol of mid-20th-century American road culture.
- Science
66 is the atomic number of dysprosium.
- History
US Route 66, established in 1926 and mostly decommissioned by 1985, was a historic highway running from Chicago to Santa Monica, California, and remains a strong symbol of mid-20th-century American road culture.
66 is part of
Factors & digit properties
- Divisors (8)
- 1, 2, 3, 6, 11, 22, 33, 66
- Prime factorisation
- 2 × 3 × 11
- Digit sum
- 12
- Digital root
- 3
Representations
- Decimal
- 66
- Binary
- 1000010
- Octal
- 102
- Hexadecimal
- 42
- Roman numeral
- LXVI
- Scientific notation
- 6.600 × 10^1
Other mathematical patterns
- Triangular number
- Palindromic number
- Abundant number
- Repdigit
- Hexagonal number
Related numbers & connections
33 is a factor of 66 (33 × 2 = 66).
View 33 →67 and 66 are consecutive integers.
View 67 →Science
66 is the atomic number of dysprosium.
DocumentedScience
History
US Route 66, established in 1926 and mostly decommissioned by 1985, was a historic highway running from Chicago to Santa Monica, California, and remains a strong symbol of mid-20th-century American road culture.
DocumentedHistoryGeography: United StatesPeriod: 1926-1985
Common questions
Is 66 a prime number?
No, 66 is not prime.
What are the factors of 66?
The factors of 66 are 1, 2, 3, 6, 11, 22, 33, 66.
What is 66 in Roman numerals?
66 in Roman numerals is LXVI.
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