The number 21318
21318 is a composite number with 32 divisors. Its prime factorisation is 2 × 3 × 11 × 17 × 19. Divisors (32): 1, 2, 3, 6, 11, 17, 19, 22, 33, 34, 38, 51, 57, 66, 102, 114 … 21318.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21318: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
21318 is composite. Its prime factorisation is
- 3
The divisors add up to 51840; without 21318 itself that is 30522, so 21318 is abundant (30522 is more than 21318). Euler's totient φ(21318) = 5760 numbers up to 21318 share no factor with it.
- 4
The digits of 21318 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 56 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21318 = 2 \times 3 \times 11 \times 17 \times 19 \]
21318 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 32 |
| Sum of divisors | 51840 |
| Euler totient φ(n) | 5760 |
| Square | 454457124 |
| Cube | 9688116969432 |
| Square root | 146.006849 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.1318 × |
21318 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand three hundred and eighteen |
| Binary (base 2) | 101001101000110 |
| Octal (base 8) | 51506 |
| Hexadecimal (base 16) | 5346 |
| Base 3 | 1002020120 |
| As time | 21318 seconds = 5 h 55 min 18 s |
Is 21318 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21318 ÷ 2 = 10659) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (21318 ÷ 3 = 7106) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 2) | 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 | Yes (21318 ÷ 6 = 3553) | 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 | No (remainder 6) | 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 | No (remainder 8) | A number is divisible by 10 if the last digit is 0. |
| 11 | Yes (21318 ÷ 11 = 1938) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 6) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21318 a prime number?
No. 21318 = 2 × 3 × 11 × 17 × 19, so it is divisible by 2.
What are the factors of 21318?
1, 2, 3, 6, 11, 17, 19, 22, 33, 34, 38, 51, 57, 66, 102, 114, 187, 209, 323, 374, 418, 561, 627, 646, 969, 1122, 1254, 1938, 3553, 7106, 10659, 21318.
What is 21318 in binary?
101001101000110 (hexadecimal 5346, octal 51506).
What is the square root of 21318?
About 146.0068.
Is 21318 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 21318?
21318 is a happy number: repeatedly adding the squares of its digits reaches 1.