The number 21480
21480 is a composite number with 32 divisors. Its prime factorisation is × 3 × 5 × 179. Divisors (32): 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 24, 30, 40, 60, 120 … 21480.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21480: a Harshad number: divisible by its digit sum 15.
- 2
21480 is composite. Its prime factorisation is
- 3
The divisors add up to 64800; without 21480 itself that is 43320, so 21480 is abundant (43320 is more than 21480). Euler's totient φ(21480) = 5696 numbers up to 21480 share no factor with it.
- 4
The digits of 21480 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 100 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21480 = 2^{3} \times 3 \times 5 \times 179 \]21480 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 32 |
| Sum of divisors | 64800 |
| Euler totient φ(n) | 5696 |
| Square | 461390400 |
| Cube | 9910665792000 |
| Square root | 146.560568 (= 2√5370) |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 100 |
| Scientific notation | 2.148 × |
21480 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand four hundred and eighty |
| Binary (base 2) | 101001111101000 |
| Octal (base 8) | 51750 |
| Hexadecimal (base 16) | 53E8 |
| Base 3 | 1002110120 |
| As time | 21480 seconds = 5 h 58 min 0 s |
Is 21480 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21480 ÷ 2 = 10740) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (21480 ÷ 3 = 7160) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (21480 ÷ 4 = 5370) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (21480 ÷ 5 = 4296) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (21480 ÷ 6 = 3580) | 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 (21480 ÷ 8 = 2685) | 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 | Yes (21480 ÷ 10 = 2148) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 8) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (21480 ÷ 12 = 1790) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21480 a prime number?
No. 21480 = × 3 × 5 × 179, so it is divisible by 2.
What are the factors of 21480?
1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 24, 30, 40, 60, 120, 179, 358, 537, 716, 895, 1074, 1432, 1790, 2148, 2685, 3580, 4296, 5370, 7160, 10740, 21480.
What is 21480 in binary?
101001111101000 (hexadecimal 53E8, octal 51750).
What is the square root of 21480?
About 146.5606, exactly 2√5370.
Is 21480 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 21480?
21480 is a Harshad number: divisible by its digit sum 15.