The number 21308
21308 is a composite number with 12 divisors. Its prime factorisation is × 7 × 761. Divisors (12): 1, 2, 4, 7, 14, 28, 761, 1522, 3044, 5327, 10654, 21308.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21308: a Harshad number: divisible by its digit sum 14.
- 2
21308 is composite. Its prime factorisation is
- 3
The divisors add up to 42672; without 21308 itself that is 21364, so 21308 is abundant (21364 is more than 21308). Euler's totient φ(21308) = 9120 numbers up to 21308 share no factor with it.
- 4
The digits of 21308 add up to 14, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 87 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21308 = 2^{2} \times 7 \times 761 \]21308 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 42672 |
| Euler totient φ(n) | 9120 |
| Square | 454030864 |
| Cube | 9674489650112 |
| Square root | 145.972600 (= 2√5327) |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 87 |
| Scientific notation | 2.1308 × |
21308 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand three hundred and eight |
| Binary (base 2) | 101001100111100 |
| Octal (base 8) | 51474 |
| Hexadecimal (base 16) | 533C |
| Base 3 | 1002020012 |
| As time | 21308 seconds = 5 h 55 min 8 s |
Is 21308 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21308 ÷ 2 = 10654) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 2) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (21308 ÷ 4 = 5327) | 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 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (21308 ÷ 7 = 3044) | 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 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 5) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 8) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 1) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21308 a prime number?
No. 21308 = × 7 × 761, so it is divisible by 2.
What are the factors of 21308?
1, 2, 4, 7, 14, 28, 761, 1522, 3044, 5327, 10654, 21308.
What is 21308 in binary?
101001100111100 (hexadecimal 533C, octal 51474).
What is the square root of 21308?
About 145.9726, exactly 2√5327.
Is 21308 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 21308?
21308 is a Harshad number: divisible by its digit sum 14.