Number reference
25 explained.
25: twenty-five, composite, perfect square; factors, prime factorization, roots, binary, hexadecimal, and digit properties.
Identity and representations
- Written form
- twenty-five
- Classification
- composite
- Factors
- 1, 5, 25
- Prime factorization
- 5 × 5
- Square root
- 5
- Cube root
- 2.924018
- Binary
- 11001
- Octal
- 31
- Hexadecimal
- 19
- Roman numeral
- XXV
- Digit sum
- 7
- Digital root
- 7
What makes 25 notable
- Perfect square. 25 = 5², so a square of side 5 has an area of 25.
25 in everyday use
Twenty-five cents make a quarter, and a twenty-fifth anniversary is silver. It is the atomic number of manganese and the date of Christmas in December. A short-course swimming pool is 25 metres long. Twenty-five percent is a quarter of anything, and Roman XXV appears on countless cornerstones. The minimum age to serve in the US House of Representatives is 25.
Twenty-five is five squared and the smallest square that is the sum of two other squares: 9 + 16, the 3-4-5 triangle again. Every square of a number ending in 5 itself ends in 25, and there is a shortcut for the rest: 35² is 3 × 4 followed by 25, or 1225. In base ten it is also an automorphic number, since 25² = 625 ends in 25.
Nearby numbers
How to read this page
The factor list shows every way 25 splits into equal whole-number groups — 3 divisors in total. The prime factorisation is the compact form of that same information, and the base conversions restate 25 for contexts that do not use decimal.
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