The number 21243
21243 is a composite number with 8 divisors. Its prime factorisation is 3 × 73 × 97. Divisors (8): 1, 3, 73, 97, 219, 291, 7081, 21243.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21243 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21243 is composite. Its prime factorisation is
- 3
The divisors add up to 29008; without 21243 itself that is 7765, so 21243 is deficient (7765 is less than 21243). Euler's totient φ(21243) = 13824 numbers up to 21243 share no factor with it.
- 4
The digits of 21243 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 100 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21243 = 3 \times 73 \times 97 \]
21243 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 29008 |
| Euler totient φ(n) | 13824 |
| Square | 451265049 |
| Cube | 9586223435907 |
| Square root | 145.749786 |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 100 |
| Scientific notation | 2.1243 × |
21243 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand two hundred and forty-three |
| Binary (base 2) | 101001011111011 |
| Octal (base 8) | 51373 |
| Hexadecimal (base 16) | 52FB |
| Base 3 | 1002010210 |
| As time | 21243 seconds = 5 h 54 min 3 s |
Is 21243 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 (21243 ÷ 3 = 7081) | 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 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 5) | 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 3) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | 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 21243 a prime number?
No. 21243 = 3 × 73 × 97, so it is divisible by 3.
What are the factors of 21243?
1, 3, 73, 97, 219, 291, 7081, 21243.
What is 21243 in binary?
101001011111011 (hexadecimal 52FB, octal 51373).
What is the square root of 21243?
About 145.7498.
Is 21243 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 21243?
It is a composite number with 8 divisors.