The number 21741
21741 is a composite number with 4 divisors. Its prime factorisation is 3 × 7247. Divisors (4): 1, 3, 7247, 21741.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21741: a semiprime: 3 × 7247, the product of two primes.
- 2
21741 is composite. Its prime factorisation is
- 3
The divisors add up to 28992; without 21741 itself that is 7251, so 21741 is deficient (7251 is less than 21741). Euler's totient φ(21741) = 14492 numbers up to 21741 share no factor with it.
- 4
The digits of 21741 add up to 15, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 118 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21741 = 3 \times 7247 \]
21741 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 28992 |
| Euler totient φ(n) | 14492 |
| Square | 472671081 |
| Cube | 10276341972021 |
| Square root | 147.448296 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 118 |
| Scientific notation | 2.1741 × |
21741 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand seven hundred and forty-one |
| Binary (base 2) | 101010011101101 |
| Octal (base 8) | 52355 |
| Hexadecimal (base 16) | 54ED |
| Base 3 | 1002211020 |
| As time | 21741 seconds = 6 h 2 min 21 s |
Is 21741 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 (21741 ÷ 3 = 7247) | 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 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 6) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 6) | 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 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21741 a prime number?
No. 21741 = 3 × 7247, so it is divisible by 3.
What are the factors of 21741?
1, 3, 7247, 21741.
What is 21741 in binary?
101010011101101 (hexadecimal 54ED, octal 52355).
What is the square root of 21741?
About 147.4483.
Is 21741 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 21741?
21741 is a semiprime: 3 × 7247, the product of two primes.