The number 18401
18401 is the 2108th prime number. Its only divisors are 1 and 18401.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 18401: the 2108th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
18401 is prime, so its only factors are 1 and 18401. It is the 2108th prime; the next prime is 18413 and the one before is 18397.
- 3
The divisors add up to 18402; without 18401 itself that is 1, so 18401 is deficient (1 is less than 18401). Euler's totient φ(18401) = 18400 numbers up to 18401 share no factor with it.
- 4
The digits of 18401 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 123 steps to reach 1.
18401 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 18402 |
| Euler totient φ(n) | 18400 |
| Square | 338596801 |
| Cube | 6230519735201 |
| Square root | 135.650286 |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 123 |
| Scientific notation | 1.8401 × |
18401 in other forms
| Form | Value |
|---|---|
| In words | eighteen thousand four hundred and one |
| Binary (base 2) | 100011111100001 |
| Octal (base 8) | 43741 |
| Hexadecimal (base 16) | 47E1 |
| Base 3 | 221020112 |
| As time | 18401 seconds = 5 h 6 min 41 s |
Is 18401 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 | No (remainder 5) | 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 1) | 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 9) | 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 18401 a prime number?
Yes. 18401 is divisible only by 1 and itself.
What are the factors of 18401?
1, 18401.
What is 18401 in binary?
100011111100001 (hexadecimal 47E1, octal 43741).
What is the square root of 18401?
About 135.6503.
Is 18401 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 18401?
18401 is the 2108th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.