The number 21024
21024 is a composite number with 36 divisors. Its prime factorisation is × × 73. Divisors (36): 1, 2, 3, 4, 6, 8, 9, 12, 16, 18, 24, 32, 36, 48, 72, 73 … 21024.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21024: a Harshad number: divisible by its digit sum 9.
- 2
21024 is composite. Its prime factorisation is
- 3
The divisors add up to 60606; without 21024 itself that is 39582, so 21024 is abundant (39582 is more than 21024). Euler's totient φ(21024) = 6912 numbers up to 21024 share no factor with it.
- 4
The digits of 21024 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 56 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21024 = 2^{5} \times 3^{2} \times 73 \]21024 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 36 |
| Sum of divisors | 60606 |
| Euler totient φ(n) | 6912 |
| Square | 442008576 |
| Cube | 9292788301824 |
| Square root | 144.996552 (= 12√146) |
| Digit sum / digital root | 9 / 9 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.1024 × |
21024 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand and twenty-four |
| Binary (base 2) | 101001000100000 |
| Octal (base 8) | 51040 |
| Hexadecimal (base 16) | 5220 |
| Base 3 | 1001211200 |
| As time | 21024 seconds = 5 h 50 min 24 s |
Is 21024 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21024 ÷ 2 = 10512) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (21024 ÷ 3 = 7008) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (21024 ÷ 4 = 5256) | 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 | Yes (21024 ÷ 6 = 3504) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 3) | 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 (21024 ÷ 8 = 2628) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (21024 ÷ 9 = 2336) | 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 3) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (21024 ÷ 12 = 1752) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21024 a prime number?
No. 21024 = × × 73, so it is divisible by 2.
What are the factors of 21024?
1, 2, 3, 4, 6, 8, 9, 12, 16, 18, 24, 32, 36, 48, 72, 73, 96, 144, 146, 219, 288, 292, 438, 584, 657, 876, 1168, 1314, 1752, 2336, 2628, 3504, 5256, 7008, 10512, 21024.
What is 21024 in binary?
101001000100000 (hexadecimal 5220, octal 51040).
What is the square root of 21024?
About 144.9966, exactly 12√146.
Is 21024 divisible by 3?
Yes. Its digits add up to 9, a multiple of 3.
What is special about the number 21024?
21024 is a Harshad number: divisible by its digit sum 9.