The number 18481
18481 is a palindromic prime: it reads the same backwards and is prime, the 2117th prime number and a palindrome: it reads 18481 backwards too. Its only divisors are 1 and 18481.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 18481: a palindromic prime: it reads the same backwards and is prime; the 2117th prime number; a palindrome: it reads 18481 backwards too.
- 2
18481 is prime, so its only factors are 1 and 18481. It is the 2117th prime; the next prime is 18493 and the one before is 18461.
- 3
The divisors add up to 18482; without 18481 itself that is 1, so 18481 is deficient (1 is less than 18481). Euler's totient φ(18481) = 18480 numbers up to 18481 share no factor with it.
- 4
The digits of 18481 add up to 22, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 154 steps to reach 1.
18481 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 18482 |
| Euler totient φ(n) | 18480 |
| Square | 341547361 |
| Cube | 6312136778641 |
| Square root | 135.944842 |
| Digit sum / digital root | 22 / 4 |
| Collatz steps to 1 | 154 |
| Scientific notation | 1.8481 × |
18481 in other forms
| Form | Value |
|---|---|
| In words | eighteen thousand four hundred and eighty-one |
| Binary (base 2) | 100100000110001 |
| Octal (base 8) | 44061 |
| Hexadecimal (base 16) | 4831 |
| Base 3 | 221100111 |
| As time | 18481 seconds = 5 h 8 min 1 s |
Is 18481 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 1) | 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 4) | 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 1) | 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 18481 a prime number?
Yes. 18481 is divisible only by 1 and itself.
What are the factors of 18481?
1, 18481.
What is 18481 in binary?
100100000110001 (hexadecimal 4831, octal 44061).
What is the square root of 18481?
About 135.9448.
Is 18481 divisible by 3?
No. Its digits add up to 22, which is not a multiple of 3.
What is special about the number 18481?
18481 is a palindromic prime: it reads the same backwards and is prime; the 2117th prime number; a palindrome: it reads 18481 backwards too.