1981
1981 is the year the IBM PC was released.
- Odd
- Composite
Where 1981 fits
Why 1981 is special
IBM built it from off-the-shelf parts and licensed rather than owned its operating system, which made compatible machines legal to build. That decision created the PC industry and cost IBM control of it within a decade.
Factors & digit properties
- Divisors (4)
- 1, 7, 283, 1981
- Prime factorisation
- 7 × 283
- Digit sum
- 19
- Digital root
- 1
Representations
- Decimal
- 1981
- Binary
- 11110111101
- Octal
- 3675
- Hexadecimal
- 7bd
- Roman numeral
- MCMLXXXI
- Scientific notation
- 1.981 × 10^3
Other mathematical patterns
- Deficient number
- Semiprime
Related numbers & connections
The Apple II and the IBM PC, four years apart. The first proved there was a home market and the second made it an industry with interchangeable parts.
View 1977 →Kodak built a digital camera in 1975 and shelved it; IBM built the PC in 1981 and licensed away control of it. Two different ways for an incumbent to lose a market it created.
View 1975 →Finance & economics
IBM built the PC from off-the-shelf parts and licensed rather than owned its operating system, which made compatible machines legal to build. That created the PC industry and cost IBM control of it inside a decade.
DocumentedFinance & economicsPeriod: 1981
Common questions
Is 1981 a prime number?
No, 1981 is not prime.
What are the factors of 1981?
The factors of 1981 are 1, 7, 283, 1981.
What is 1981 in Roman numerals?
1981 in Roman numerals is MCMLXXXI.
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