The number 3121
3121 is a twin prime (3119 and 3121 are both prime) and the 445th prime number. Its only divisors are 1 and 3121.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 3121: a twin prime (3119 and 3121 are both prime); the 445th prime number.
- 2
3121 is prime, so its only factors are 1 and 3121. It is the 445th prime; the next prime is 3137 and the one before is 3119.
- 3
The divisors add up to 3122; without 3121 itself that is 1, so 3121 is deficient (1 is less than 3121). Euler's totient φ(3121) = 3120 numbers up to 3121 share no factor with it.
- 4
The digits of 3121 add up to 7, 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.
3121 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 3122 |
| Euler totient φ(n) | 3120 |
| Square | 9740641 |
| Cube | 30400540561 |
| Square root | 55.865911 |
| Digit sum / digital root | 7 / 7 |
| Collatz steps to 1 | 61 |
| Scientific notation | 3.121 × |
3121 in other forms
| Form | Value |
|---|---|
| In words | three thousand one hundred and twenty-one |
| Roman numerals | MMMCXXI |
| Binary (base 2) | 110000110001 |
| Octal (base 8) | 6061 |
| Hexadecimal (base 16) | C31 |
| Base 3 | 11021121 |
| As time | 3121 seconds = 52 min 1 s |
Is 3121 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 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 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 8) | 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 3121 a prime number?
Yes. 3121 is divisible only by 1 and itself.
What are the factors of 3121?
1, 3121.
What is 3121 in binary?
110000110001 (hexadecimal C31, octal 6061).
What is the square root of 3121?
About 55.8659.
What is 3121 in Roman numerals?
MMMCXXI.
Is 3121 divisible by 3?
No. Its digits add up to 7, which is not a multiple of 3.
What is special about the number 3121?
3121 is a twin prime (3119 and 3121 are both prime); the 445th prime number.