The number 31121
31121 is a twin prime (31121 and 31123 are both prime) and the 3351st prime number. Its only divisors are 1 and 31121.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31121: a twin prime (31121 and 31123 are both prime); the 3351st prime number.
- 2
31121 is prime, so its only factors are 1 and 31121. It is the 3351st prime; the next prime is 31123 and the one before is 31091.
- 3
The divisors add up to 31122; without 31121 itself that is 1, so 31121 is deficient (1 is less than 31121). Euler's totient φ(31121) = 31120 numbers up to 31121 share no factor with it.
- 4
The digits of 31121 add up to 8, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 85 steps to reach 1.
31121 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 31122 |
| Euler totient φ(n) | 31120 |
| Square | 968516641 |
| Cube | 30141206384561 |
| Square root | 176.411451 |
| Digit sum / digital root | 8 / 8 |
| Collatz steps to 1 | 85 |
| Scientific notation | 3.1121 × |
31121 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand one hundred and twenty-one |
| Binary (base 2) | 111100110010001 |
| Octal (base 8) | 74621 |
| Hexadecimal (base 16) | 7991 |
| Base 3 | 1120200122 |
| As time | 31121 seconds = 8 h 38 min 41 s |
Is 31121 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 6) | 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 8) | 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 2) | 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 31121 a prime number?
Yes. 31121 is divisible only by 1 and itself.
What are the factors of 31121?
1, 31121.
What is 31121 in binary?
111100110010001 (hexadecimal 7991, octal 74621).
What is the square root of 31121?
About 176.4115.
Is 31121 divisible by 3?
No. Its digits add up to 8, which is not a multiple of 3.
What is special about the number 31121?
31121 is a twin prime (31121 and 31123 are both prime); the 3351st prime number.