The number 18421
18421 is a composite number with 6 divisors. Its prime factorisation is Ć 109. Divisors (6): 1, 13, 109, 169, 1417, 18421.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 18421: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
18421 is composite. Its prime factorisation is
- 3
The divisors add up to 20130; without 18421 itself that is 1709, so 18421 is deficient (1709 is less than 18421). Euler's totient Ļ(18421) = 16848 numbers up to 18421 share no factor with it.
- 4
The digits of 18421 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 61 steps to reach 1.
LaTeX source of the formulas on this page
\[ 18421 = 13^{2} \times 109 \]18421 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 20130 |
| Euler totient Ļ(n) | 16848 |
| Square | 339333241 |
| Cube | 6250857632461 |
| Square root | 135.723985 (= 13ā109) |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 61 |
| Scientific notation | 1.8421 Ć |
18421 in other forms
| Form | Value |
|---|---|
| In words | eighteen thousand four hundred and twenty-one |
| Binary (base 2) | 100011111110101 |
| Octal (base 8) | 43765 |
| Hexadecimal (base 16) | 47F5 |
| Base 3 | 221021021 |
| As time | 18421 seconds = 5 h 7 min 1 s |
Is 18421 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 1) | 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 1) | 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 | No (remainder 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | 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 7) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 18421 a prime number?
No. 18421 = Ć 109, so it is divisible by 13.
What are the factors of 18421?
1, 13, 109, 169, 1417, 18421.
What is 18421 in binary?
100011111110101 (hexadecimal 47F5, octal 43765).
What is the square root of 18421?
About 135.7240, exactly 13ā109.
Is 18421 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 18421?
18421 is a happy number: repeatedly adding the squares of its digits reaches 1.