2001
2001 is the year of the September 11 attacks, and the year Wikipedia launched.
- Odd
- Composite
Where 2001 fits
Why 2001 is special
2001 is remembered almost entirely for one September morning, and the security, legal and foreign-policy consequences that followed for decades. It is also the year Wikipedia began in January — an unrelated event that turned out to reshape how a generation looks things up.
Factors & digit properties
- Divisors (8)
- 1, 3, 23, 29, 69, 87, 667, 2001
- Prime factorisation
- 3 × 23 × 29
- Digit sum
- 3
- Digital root
- 3
Representations
- Decimal
- 2001
- Binary
- 11111010001
- Octal
- 3721
- Hexadecimal
- 7d1
- Roman numeral
- MMI
- Scientific notation
- 2.001 × 10^3
Other mathematical patterns
- Deficient number
- Harshad (Niven) number
- Lucky number (mathematical sieve)
Related numbers & connections
The American emergency number and the date of the 2001 attacks are written with the same three digits, distinguished in print only by punctuation.
View 911 →Technology & computing
Wikipedia launched on 15 January 2001, initially as a side project to feed a peer-reviewed encyclopedia that never took off. Within a year the side project had far outgrown the parent. Its founding predates the September attacks that define the year in most other respects by eight months.
DocumentedTechnology & computingPeriod: 15 January 2001
Common questions
Is 2001 a prime number?
No, 2001 is not prime.
What are the factors of 2001?
The factors of 2001 are 1, 3, 23, 29, 69, 87, 667, 2001.
What is 2001 in Roman numerals?
2001 in Roman numerals is MMI.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 1 reviewer-confirmed record, sourced and reviewed before publication.
Last reviewed: 3 August 2026