The number 21141
21141 is a composite number with 14 divisors. Its prime factorisation is × 29. Divisors (14): 1, 3, 9, 27, 29, 81, 87, 243, 261, 729, 783, 2349, 7047, 21141.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21141: a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 9.
- 2
21141 is composite. Its prime factorisation is
- 3
The divisors add up to 32790; without 21141 itself that is 11649, so 21141 is deficient (11649 is less than 21141). Euler's totient φ(21141) = 13608 numbers up to 21141 share no factor with it.
- 4
The digits of 21141 add up to 9, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 105 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21141 = 3^{6} \times 29 \]21141 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 14 |
| Sum of divisors | 32790 |
| Euler totient φ(n) | 13608 |
| Square | 446941881 |
| Cube | 9448798306221 |
| Square root | 145.399450 (= 27√29) |
| Digit sum / digital root | 9 / 9 |
| Collatz steps to 1 | 105 |
| Scientific notation | 2.1141 × |
21141 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand one hundred and forty-one |
| Binary (base 2) | 101001010010101 |
| Octal (base 8) | 51225 |
| Hexadecimal (base 16) | 5295 |
| Base 3 | 1002000000 |
| As time | 21141 seconds = 5 h 52 min 21 s |
Is 21141 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 (21141 ÷ 3 = 7047) | 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 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (21141 ÷ 9 = 2349) | 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 10) | 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 21141 a prime number?
No. 21141 = × 29, so it is divisible by 3.
What are the factors of 21141?
1, 3, 9, 27, 29, 81, 87, 243, 261, 729, 783, 2349, 7047, 21141.
What is 21141 in binary?
101001010010101 (hexadecimal 5295, octal 51225).
What is the square root of 21141?
About 145.3994, exactly 27√29.
Is 21141 divisible by 3?
Yes. Its digits add up to 9, a multiple of 3.
What is special about the number 21141?
21141 is a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 9.