The number 1243
1243 is a composite number with 4 divisors. Its prime factorisation is 11 × 113. Divisors (4): 1, 11, 113, 1243.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 1243: a semiprime: 11 × 113, the product of two primes.
- 2
1243 is composite. Its prime factorisation is
- 3
The divisors add up to 1368; without 1243 itself that is 125, so 1243 is deficient (125 is less than 1243). Euler's totient φ(1243) = 1120 numbers up to 1243 share no factor with it.
- 4
The digits of 1243 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 70 steps to reach 1.
LaTeX source of the formulas on this page
\[ 1243 = 11 \times 113 \]
1243 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 1368 |
| Euler totient φ(n) | 1120 |
| Square | 1545049 |
| Cube | 1920495907 |
| Square root | 35.256205 |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 70 |
| Scientific notation | 1.243 × |
1243 in other forms
| Form | Value |
|---|---|
| In words | one thousand two hundred and forty-three |
| Roman numerals | MCCXLIII |
| Binary (base 2) | 10011011011 |
| Octal (base 8) | 2333 |
| Hexadecimal (base 16) | 4DB |
| Base 3 | 1201001 |
| As time | 1243 seconds = 20 min 43 s |
Is 1243 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 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 3) | 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 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 3) | 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 3) | A number is divisible by 10 if the last digit is 0. |
| 11 | Yes (1243 ÷ 11 = 113) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 1243 a prime number?
No. 1243 = 11 × 113, so it is divisible by 11.
What are the factors of 1243?
1, 11, 113, 1243.
What is 1243 in binary?
10011011011 (hexadecimal 4DB, octal 2333).
What is the square root of 1243?
About 35.2562.
What is 1243 in Roman numerals?
MCCXLIII.
Is 1243 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 1243?
1243 is a semiprime: 11 × 113, the product of two primes.