The number 21043
21043 is a composite number with 4 divisors. Its prime factorisation is 11 × 1913. Divisors (4): 1, 11, 1913, 21043.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21043: a semiprime: 11 × 1913, the product of two primes.
- 2
21043 is composite. Its prime factorisation is
- 3
The divisors add up to 22968; without 21043 itself that is 1925, so 21043 is deficient (1925 is less than 21043). Euler's totient φ(21043) = 19120 numbers up to 21043 share no factor with it.
- 4
The digits of 21043 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 105 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21043 = 11 \times 1913 \]
21043 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 22968 |
| Euler totient φ(n) | 19120 |
| Square | 442807849 |
| Cube | 9318005566507 |
| Square root | 145.062056 |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 105 |
| Scientific notation | 2.1043 × |
21043 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand and forty-three |
| Binary (base 2) | 101001000110011 |
| Octal (base 8) | 51063 |
| Hexadecimal (base 16) | 5233 |
| Base 3 | 1001212101 |
| As time | 21043 seconds = 5 h 50 min 43 s |
Is 21043 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 1) | 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 (21043 ÷ 11 = 1913) | 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 21043 a prime number?
No. 21043 = 11 × 1913, so it is divisible by 11.
What are the factors of 21043?
1, 11, 1913, 21043.
What is 21043 in binary?
101001000110011 (hexadecimal 5233, octal 51063).
What is the square root of 21043?
About 145.0621.
Is 21043 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 21043?
21043 is a semiprime: 11 × 1913, the product of two primes.