The number 1081
1081 is a triangular number: 1 + 2 + … + 46 = 1081. Its prime factorisation is 23 × 47. Divisors (4): 1, 23, 47, 1081.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 1081: a triangular number: 1 + 2 + … + 46 = 1081; a semiprime: 23 × 47, the product of two primes.
- 2
1081 is composite. Its prime factorisation is
- 3
The divisors add up to 1152; without 1081 itself that is 71, so 1081 is deficient (71 is less than 1081). Euler's totient φ(1081) = 1012 numbers up to 1081 share no factor with it.
- 4
The digits of 1081 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 137 steps to reach 1.
LaTeX source of the formulas on this page
\[ 1081 = 23 \times 47 \]
1081 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 1152 |
| Euler totient φ(n) | 1012 |
| Square | 1168561 |
| Cube | 1263214441 |
| Square root | 32.878564 |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 137 |
| Scientific notation | 1.081 × |
1081 in other forms
| Form | Value |
|---|---|
| In words | one thousand and eighty-one |
| Roman numerals | MLXXXI |
| Binary (base 2) | 10000111001 |
| Octal (base 8) | 2071 |
| Hexadecimal (base 16) | 439 |
| Base 3 | 1111001 |
| As time | 1081 seconds = 18 min 1 s |
Is 1081 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 | No (remainder 3) | 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 3) | 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 1081 a prime number?
No. 1081 = 23 × 47, so it is divisible by 23.
What are the factors of 1081?
1, 23, 47, 1081.
What is 1081 in binary?
10000111001 (hexadecimal 439, octal 2071).
What is the square root of 1081?
About 32.8786.
What is 1081 in Roman numerals?
MLXXXI.
Is 1081 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 1081?
1081 is a triangular number: 1 + 2 + … + 46 = 1081; a semiprime: 23 × 47, the product of two primes.