The number 8281
8281 is a perfect square (91²). Its prime factorisation is × . Divisors (9): 1, 7, 13, 49, 91, 169, 637, 1183, 8281.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 8281: a perfect square (91²); a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
8281 is composite. Its prime factorisation is
- 3
The divisors add up to 10431; without 8281 itself that is 2150, so 8281 is deficient (2150 is less than 8281). Euler's totient φ(8281) = 6552 numbers up to 8281 share no factor with it.
- 4
The digits of 8281 add up to 19, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 158 steps to reach 1.
LaTeX source of the formulas on this page
\[ 8281 = 7^{2} \times 13^{2} \]8281 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 9 |
| Sum of divisors | 10431 |
| Euler totient φ(n) | 6552 |
| Square | 68574961 |
| Cube | 567869252041 |
| Square root | 91 |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 158 |
| Scientific notation | 8.281 × |
| Perfect power |
8281 in other forms
| Form | Value |
|---|---|
| In words | eight thousand two hundred and eighty-one |
| Binary (base 2) | 10000001011001 |
| Octal (base 8) | 20131 |
| Hexadecimal (base 16) | 2059 |
| Base 3 | 102100201 |
| As time | 8281 seconds = 2 h 18 min 1 s |
Is 8281 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 | No (remainder 1) | 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 (8281 ÷ 7 = 1183) | 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 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | 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 8281 a prime number?
No. 8281 = × , so it is divisible by 7.
What are the factors of 8281?
1, 7, 13, 49, 91, 169, 637, 1183, 8281.
What is 8281 in binary?
10000001011001 (hexadecimal 2059, octal 20131).
What is the square root of 8281?
91, because 91 × 91 = 8281.
Is 8281 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 8281?
8281 is a perfect square (91²); a happy number: repeatedly adding the squares of its digits reaches 1.