1955
1955 is the year the polio vaccine was declared safe and effective.
- Odd
- Composite
Where 1955 fits
Why 1955 is special
Salk declined to patent it, and asked who would patent the sun. Polio cases in the United States fell by roughly 90 percent within five years, and the disease is now close to eradicated worldwide.
Factors & digit properties
- Divisors (8)
- 1, 5, 17, 23, 85, 115, 391, 1955
- Prime factorisation
- 5 × 17 × 23
- Digit sum
- 20
- Digital root
- 2
Representations
- Decimal
- 1955
- Binary
- 11110100011
- Octal
- 3643
- Hexadecimal
- 7a3
- Roman numeral
- MCMLV
- Scientific notation
- 1.955 × 10^3
Other mathematical patterns
- Deficient number
Related numbers & connections
Insulin's discoverers sold the patent for a dollar in 1921 and Salk declined to patent the polio vaccine in 1955. Both decisions are cited in every modern argument about drug pricing.
View 1921 →Science
The Salk vaccine was declared safe and effective in 1955 and was not patented — Salk asked who would patent the sun. US polio cases fell roughly 90 percent within five years and the disease is now close to global eradication.
DocumentedSciencePeriod: 1955
Common questions
Is 1955 a prime number?
No, 1955 is not prime.
What are the factors of 1955?
The factors of 1955 are 1, 5, 17, 23, 85, 115, 391, 1955.
What is 1955 in Roman numerals?
1955 in Roman numerals is MCMLV.
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