The number 18221
18221 is a composite number with 8 divisors. Its prime factorisation is 7 × 19 × 137. Divisors (8): 1, 7, 19, 133, 137, 959, 2603, 18221.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
18221 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
18221 is composite. Its prime factorisation is
- 3
The divisors add up to 22080; without 18221 itself that is 3859, so 18221 is deficient (3859 is less than 18221). Euler's totient φ(18221) = 14688 numbers up to 18221 share no factor with it.
- 4
The digits of 18221 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 61 steps to reach 1.
LaTeX source of the formulas on this page
\[ 18221 = 7 \times 19 \times 137 \]
18221 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 22080 |
| Euler totient φ(n) | 14688 |
| Square | 332004841 |
| Cube | 6049460207861 |
| Square root | 134.985184 |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 61 |
| Scientific notation | 1.8221 × |
18221 in other forms
| Form | Value |
|---|---|
| In words | eighteen thousand two hundred and twenty-one |
| Binary (base 2) | 100011100101101 |
| Octal (base 8) | 43455 |
| Hexadecimal (base 16) | 472D |
| Base 3 | 220222212 |
| As time | 18221 seconds = 5 h 3 min 41 s |
Is 18221 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | 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 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (18221 ÷ 7 = 2603) | 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 5) | 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 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 18221 a prime number?
No. 18221 = 7 × 19 × 137, so it is divisible by 7.
What are the factors of 18221?
1, 7, 19, 133, 137, 959, 2603, 18221.
What is 18221 in binary?
100011100101101 (hexadecimal 472D, octal 43455).
What is the square root of 18221?
About 134.9852.
Is 18221 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 18221?
It is a composite number with 8 divisors.