The number 1161
1161 is a binary palindrome (10010001001). Its prime factorisation is × 43. Divisors (8): 1, 3, 9, 27, 43, 129, 387, 1161.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 1161: a binary palindrome (10010001001); a Harshad number: divisible by its digit sum 9.
- 2
1161 is composite. Its prime factorisation is
- 3
The divisors add up to 1760; without 1161 itself that is 599, so 1161 is deficient (599 is less than 1161). Euler's totient φ(1161) = 756 numbers up to 1161 share no factor with it.
- 4
The digits of 1161 add up to 9, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 181 steps to reach 1.
LaTeX source of the formulas on this page
\[ 1161 = 3^{3} \times 43 \]1161 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 1760 |
| Euler totient φ(n) | 756 |
| Square | 1347921 |
| Cube | 1564936281 |
| Square root | 34.073450 (= 3√129) |
| Digit sum / digital root | 9 / 9 |
| Collatz steps to 1 | 181 |
| Scientific notation | 1.161 × |
1161 in other forms
| Form | Value |
|---|---|
| In words | one thousand one hundred and sixty-one |
| Roman numerals | MCLXI |
| Binary (base 2) | 10010001001 |
| Octal (base 8) | 2211 |
| Hexadecimal (base 16) | 489 |
| Base 3 | 1121000 |
| As time | 1161 seconds = 19 min 21 s |
Is 1161 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 (1161 ÷ 3 = 387) | 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 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 6) | 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 (1161 ÷ 9 = 129) | 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 6) | 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 1161 a prime number?
No. 1161 = × 43, so it is divisible by 3.
What are the factors of 1161?
1, 3, 9, 27, 43, 129, 387, 1161.
What is 1161 in binary?
10010001001 (hexadecimal 489, octal 2211).
What is the square root of 1161?
About 34.0735, exactly 3√129.
What is 1161 in Roman numerals?
MCLXI.
Is 1161 divisible by 3?
Yes. Its digits add up to 9, a multiple of 3.
What is special about the number 1161?
1161 is a binary palindrome (10010001001); a Harshad number: divisible by its digit sum 9.