The number 21424
21424 is a composite number with 20 divisors. Its prime factorisation is × 13 × 103. Divisors (20): 1, 2, 4, 8, 13, 16, 26, 52, 103, 104, 206, 208, 412, 824, 1339, 1648 … 21424.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21424: a Harshad number: divisible by its digit sum 13.
- 2
21424 is composite. Its prime factorisation is
- 3
The divisors add up to 45136; without 21424 itself that is 23712, so 21424 is abundant (23712 is more than 21424). Euler's totient φ(21424) = 9792 numbers up to 21424 share no factor with it.
- 4
The digits of 21424 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 30 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21424 = 2^{4} \times 13 \times 103 \]21424 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 20 |
| Sum of divisors | 45136 |
| Euler totient φ(n) | 9792 |
| Square | 458987776 |
| Cube | 9833354113024 |
| Square root | 146.369396 (= 4√1339) |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 30 |
| Scientific notation | 2.1424 × |
21424 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand four hundred and twenty-four |
| Binary (base 2) | 101001110110000 |
| Octal (base 8) | 51660 |
| Hexadecimal (base 16) | 53B0 |
| Base 3 | 1002101111 |
| As time | 21424 seconds = 5 h 57 min 4 s |
Is 21424 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21424 ÷ 2 = 10712) | 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 | Yes (21424 ÷ 4 = 5356) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 4) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 4) | 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 | Yes (21424 ÷ 8 = 2678) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 4) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 7) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 4) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21424 a prime number?
No. 21424 = × 13 × 103, so it is divisible by 2.
What are the factors of 21424?
1, 2, 4, 8, 13, 16, 26, 52, 103, 104, 206, 208, 412, 824, 1339, 1648, 2678, 5356, 10712, 21424.
What is 21424 in binary?
101001110110000 (hexadecimal 53B0, octal 51660).
What is the square root of 21424?
About 146.3694, exactly 4√1339.
Is 21424 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 21424?
21424 is a Harshad number: divisible by its digit sum 13.