The number 1225
1225 is a perfect square (35²) and a triangular number: 1 + 2 + … + 49 = 1225. Its prime factorisation is × . Divisors (9): 1, 5, 7, 25, 35, 49, 175, 245, 1225.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 1225: a perfect square (35²); a triangular number: 1 + 2 + … + 49 = 1225.
- 2
1225 is composite. Its prime factorisation is
- 3
The divisors add up to 1767; without 1225 itself that is 542, so 1225 is deficient (542 is less than 1225). Euler's totient φ(1225) = 840 numbers up to 1225 share no factor with it.
- 4
The digits of 1225 add up to 10, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 132 steps to reach 1.
LaTeX source of the formulas on this page
\[ 1225 = 5^{2} \times 7^{2} \]1225 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 9 |
| Sum of divisors | 1767 |
| Euler totient φ(n) | 840 |
| Square | 1500625 |
| Cube | 1838265625 |
| Square root | 35 |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 132 |
| Scientific notation | 1.225 × |
| Perfect power |
1225 in other forms
| Form | Value |
|---|---|
| In words | one thousand two hundred and twenty-five |
| Roman numerals | MCCXXV |
| Binary (base 2) | 10011001001 |
| Octal (base 8) | 2311 |
| Hexadecimal (base 16) | 4C9 |
| Base 3 | 1200101 |
| As time | 1225 seconds = 20 min 25 s |
Is 1225 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 1) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (1225 ÷ 5 = 245) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (1225 ÷ 7 = 175) | A number is divisible by 7 if double the last digit and subtract it from the rest: the result is a multiple of 7. |
| 8 | No (remainder 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 1) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 5) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 4) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 1225 a prime number?
No. 1225 = × , so it is divisible by 5.
What are the factors of 1225?
1, 5, 7, 25, 35, 49, 175, 245, 1225.
What is 1225 in binary?
10011001001 (hexadecimal 4C9, octal 2311).
What is the square root of 1225?
35, because 35 × 35 = 1225.
What is 1225 in Roman numerals?
MCCXXV.
Is 1225 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 1225?
1225 is a perfect square (35²); a triangular number: 1 + 2 + … + 49 = 1225.