The number 81225
81225 is a perfect square (285²). Its prime factorisation is × × . Divisors (27): 1, 3, 5, 9, 15, 19, 25, 45, 57, 75, 95, 171, 225, 285, 361, 475 … 81225.
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How to work it out
- 1
What is special about 81225: a perfect square (285²).
- 2
81225 is composite. Its prime factorisation is
- 3
The divisors add up to 153543; without 81225 itself that is 72318, so 81225 is deficient (72318 is less than 81225). Euler's totient φ(81225) = 41040 numbers up to 81225 share no factor with it.
- 4
The digits of 81225 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 138 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81225 = 3^{2} \times 5^{2} \times 19^{2} \]81225 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 27 |
| Sum of divisors | 153543 |
| Euler totient φ(n) | 41040 |
| Square | 6597500625 |
| Cube | 535881988265625 |
| Square root | 285 |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 138 |
| Scientific notation | 8.1225 × |
| Perfect power |
81225 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand two hundred and twenty-five |
| Binary (base 2) | 10011110101001001 |
| Octal (base 8) | 236511 |
| Hexadecimal (base 16) | 13D49 |
| Base 3 | 11010102100 |
| As time | 81225 seconds = 22 h 33 min 45 s |
Is 81225 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 | Yes (81225 ÷ 3 = 27075) | 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 (81225 ÷ 5 = 16245) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 4) | 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 | Yes (81225 ÷ 9 = 9025) | 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 1) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 81225 a prime number?
No. 81225 = × × , so it is divisible by 3.
What are the factors of 81225?
1, 3, 5, 9, 15, 19, 25, 45, 57, 75, 95, 171, 225, 285, 361, 475, 855, 1083, 1425, 1805, 3249, 4275, 5415, 9025, 16245, 27075, 81225.
What is 81225 in binary?
10011110101001001 (hexadecimal 13D49, octal 236511).
What is the square root of 81225?
285, because 285 × 285 = 81225.
Is 81225 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 81225?
81225 is a perfect square (285²).