The number 18121
18121 is a twin prime (18119 and 18121 are both prime) and the 2076th prime number. Its only divisors are 1 and 18121.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 18121: a twin prime (18119 and 18121 are both prime); the 2076th prime number.
- 2
18121 is prime, so its only factors are 1 and 18121. It is the 2076th prime; the next prime is 18127 and the one before is 18119.
- 3
The divisors add up to 18122; without 18121 itself that is 1, so 18121 is deficient (1 is less than 18121). Euler's totient φ(18121) = 18120 numbers up to 18121 share no factor with it.
- 4
The digits of 18121 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 40 steps to reach 1.
18121 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 18122 |
| Euler totient φ(n) | 18120 |
| Square | 328370641 |
| Cube | 5950404385561 |
| Square root | 134.614264 |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 40 |
| Scientific notation | 1.8121 × |
18121 in other forms
| Form | Value |
|---|---|
| In words | eighteen thousand one hundred and twenty-one |
| Binary (base 2) | 100011011001001 |
| Octal (base 8) | 43311 |
| Hexadecimal (base 16) | 46C9 |
| Base 3 | 220212011 |
| As time | 18121 seconds = 5 h 2 min 1 s |
Is 18121 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 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 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 4) | 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 18121 a prime number?
Yes. 18121 is divisible only by 1 and itself.
What are the factors of 18121?
1, 18121.
What is 18121 in binary?
100011011001001 (hexadecimal 46C9, octal 43311).
What is the square root of 18121?
About 134.6143.
Is 18121 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 18121?
18121 is a twin prime (18119 and 18121 are both prime); the 2076th prime number.