17
17 is a prime number, the atomic number of chlorine, and the total syllable count of a traditional Japanese haiku (5-7-5).
- Odd
- Prime
Where 17 fits
Why 17 is special
17 is also one of only two prime-numbered life-cycle lengths (with 13) seen in periodical cicada broods — a genuinely studied case of a prime number appearing in nature.
Same number, different meanings
How 17 is understood across different contexts — never implying one meaning because of another.
- Mathematics
17 is also one of only two prime-numbered life-cycle lengths (with 13) seen in periodical cicada broods — a genuinely studied case of a prime number appearing in nature.
- Science
17 is the atomic number of chlorine.
- Culture
A traditional Japanese haiku follows a 5-7-5 syllable (strictly, 'on') structure across three lines, totalling 17 — one of the most widely taught facts about the form outside Japan, though real haiku composition is more nuanced than the syllable count alone.
17 is part of
Factors & digit properties
- Divisors (2)
- 1, 17
- Prime factorisation
- 17
- Digit sum
- 8
- Digital root
- 8
Representations
- Decimal
- 17
- Binary
- 10001
- Octal
- 21
- Hexadecimal
- 11
- Roman numeral
- XVII
- Scientific notation
- 1.700 × 10^1
Other mathematical patterns
- Deficient number
- Twin prime
Related numbers & connections
17 is a factor of 51 (17 × 3 = 51).
View 51 →17 and 19 are twin primes — two primes exactly two apart.
View 19 →17 is one of the two prime-numbered life-cycle lengths (13 or 17 years) seen in periodical cicada broods.
Mathematically related
Shares a distinctive class
- is associated with19
why?
Strength 0.50, confidence "high".
Numbers Around Us
- appears inPeriodical cicada emergence cycles
why?
Strength 0.50, confidence "high".
Science
17 is the atomic number of chlorine.
DocumentedScience
Culture
A traditional Japanese haiku follows a 5-7-5 syllable (strictly, 'on') structure across three lines, totalling 17 — one of the most widely taught facts about the form outside Japan, though real haiku composition is more nuanced than the syllable count alone.
Widely documentedCultureCulture: Japanese
Common questions
Is 17 a prime number?
Yes, 17 is prime — it has exactly two positive divisors: 1 and itself.
What are the factors of 17?
The factors of 17 are 1, 17.
What is 17 in Roman numerals?
17 in Roman numerals is XVII.
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