1557
1557 is the year the equals sign was introduced.
- Odd
- Composite
Where 1557 fits
Why 1557 is special
Robert Recorde used two parallel lines because, as he wrote, no two things can be more equal. It took about a century to displace writing the word out in full.
1557 is part of
Factors & digit properties
- Divisors (6)
- 1, 3, 9, 173, 519, 1557
- Prime factorisation
- 3^2 × 173
- Digit sum
- 18
- Digital root
- 9
Representations
- Decimal
- 1557
- Binary
- 11000010101
- Octal
- 3025
- Hexadecimal
- 615
- Roman numeral
- MDLVII
- Scientific notation
- 1.557 × 10^3
Other mathematical patterns
- Deficient number
- Happy number
Mathematics
Recorde introduced = in 1557 with an explicit justification: two lines of the same length are as equal as anything can be. Notation is invented, and the reasons are sometimes recorded.
DocumentedMathematicsGeography: WalesPeriod: 1557
Common questions
Is 1557 a prime number?
No, 1557 is not prime.
What are the factors of 1557?
The factors of 1557 are 1, 3, 9, 173, 519, 1557.
What is 1557 in Roman numerals?
1557 in Roman numerals is MDLVII.
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