The number 21360
21360 is a composite number with 40 divisors. Its prime factorisation is × 3 × 5 × 89. Divisors (40): 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 16, 20, 24, 30, 40, 48 … 21360.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21360: a Harshad number: divisible by its digit sum 12.
- 2
21360 is composite. Its prime factorisation is
- 3
The divisors add up to 66960; without 21360 itself that is 45600, so 21360 is abundant (45600 is more than 21360). Euler's totient φ(21360) = 5632 numbers up to 21360 share no factor with it.
- 4
The digits of 21360 add up to 12, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 149 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21360 = 2^{4} \times 3 \times 5 \times 89 \]21360 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 40 |
| Sum of divisors | 66960 |
| Euler totient φ(n) | 5632 |
| Square | 456249600 |
| Cube | 9745491456000 |
| Square root | 146.150607 (= 4√1335) |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 149 |
| Scientific notation | 2.136 × |
21360 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand three hundred and sixty |
| Binary (base 2) | 101001101110000 |
| Octal (base 8) | 51560 |
| Hexadecimal (base 16) | 5370 |
| Base 3 | 1002022010 |
| As time | 21360 seconds = 5 h 56 min 0 s |
Is 21360 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21360 ÷ 2 = 10680) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (21360 ÷ 3 = 7120) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (21360 ÷ 4 = 5340) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (21360 ÷ 5 = 4272) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (21360 ÷ 6 = 3560) | 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 (21360 ÷ 8 = 2670) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (21360 ÷ 10 = 2136) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (21360 ÷ 12 = 1780) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21360 a prime number?
No. 21360 = × 3 × 5 × 89, so it is divisible by 2.
What are the factors of 21360?
1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 16, 20, 24, 30, 40, 48, 60, 80, 89, 120, 178, 240, 267, 356, 445, 534, 712, 890, 1068, 1335, 1424, 1780, 2136, 2670, 3560, 4272, 5340, 7120, 10680, 21360.
What is 21360 in binary?
101001101110000 (hexadecimal 5370, octal 51560).
What is the square root of 21360?
About 146.1506, exactly 4√1335.
Is 21360 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 21360?
21360 is a Harshad number: divisible by its digit sum 12.