The number 1155
1155 is a composite number with 16 divisors. Its prime factorisation is 3 × 5 × 7 × 11. Divisors (16): 1, 3, 5, 7, 11, 15, 21, 33, 35, 55, 77, 105, 165, 231, 385, 1155.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
1155 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
1155 is composite. Its prime factorisation is
- 3
The divisors add up to 2304; without 1155 itself that is 1149, so 1155 is deficient (1149 is less than 1155). Euler's totient φ(1155) = 480 numbers up to 1155 share no factor with it.
- 4
The digits of 1155 add up to 12, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 31 steps to reach 1.
LaTeX source of the formulas on this page
\[ 1155 = 3 \times 5 \times 7 \times 11 \]
1155 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 2304 |
| Euler totient φ(n) | 480 |
| Square | 1334025 |
| Cube | 1540798875 |
| Square root | 33.985291 |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 31 |
| Scientific notation | 1.155 × |
1155 in other forms
| Form | Value |
|---|---|
| In words | one thousand one hundred and fifty-five |
| Roman numerals | MCLV |
| Binary (base 2) | 10010000011 |
| Octal (base 8) | 2203 |
| Hexadecimal (base 16) | 483 |
| Base 3 | 1120210 |
| As time | 1155 seconds = 19 min 15 s |
Is 1155 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 (1155 ÷ 3 = 385) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (1155 ÷ 5 = 231) | 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 | Yes (1155 ÷ 7 = 165) | 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | 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 | Yes (1155 ÷ 11 = 105) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 1155 a prime number?
No. 1155 = 3 × 5 × 7 × 11, so it is divisible by 3.
What are the factors of 1155?
1, 3, 5, 7, 11, 15, 21, 33, 35, 55, 77, 105, 165, 231, 385, 1155.
What is 1155 in binary?
10010000011 (hexadecimal 483, octal 2203).
What is the square root of 1155?
About 33.9853.
What is 1155 in Roman numerals?
MCLV.
Is 1155 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 1155?
It is a composite number with 16 divisors.