1225
1,225 is both a perfect square and a triangular number.
Where 1225 fits
Why 1225 is special
It is 35 squared and the sum of the numbers from 1 to 49. Numbers that are both are rare and thin out quickly — 1, 36, 1225, 41616 — and they satisfy a Pell equation, which is why they can be generated rather than searched for.
1225 is part of
Factors & digit properties
- Divisors (9)
- 1, 5, 7, 25, 35, 49, 175, 245, 1225
- Prime factorisation
- 5^2 × 7^2
- Digit sum
- 10
- Digital root
- 1
Representations
- Decimal
- 1225
- Binary
- 10011001001
- Octal
- 2311
- Hexadecimal
- 4c9
- Roman numeral
- MCCXXV
- Scientific notation
- 1.225 × 10^3
Other mathematical patterns
- Triangular number
- Deficient number
- Powerful number
- Hexagonal number
Related numbers & connections
Both are square and triangular at once. The sequence runs 1, 36, 1225, 41616 and thins so fast that the fourth term is already beyond most catalogues.
View 36 →Mathematics
1,225 is 35 squared and also 1 + 2 + … + 49. Square triangular numbers are scarce and follow a generating rule from Pell's equation, so the sequence can be produced directly rather than found by testing.
DocumentedMathematics
Common questions
Is 1225 a prime number?
No, 1225 is not prime.
What are the factors of 1225?
The factors of 1225 are 1, 5, 7, 25, 35, 49, 175, 245, 1225.
What is 1225 in Roman numerals?
1225 in Roman numerals is MCCXXV.
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