The number 1231
1231 is a twin prime (1229 and 1231 are both prime) and the 202nd prime number. Its only divisors are 1 and 1231.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 1231: a twin prime (1229 and 1231 are both prime); the 202nd prime number.
- 2
1231 is prime, so its only factors are 1 and 1231. It is the 202nd prime; the next prime is 1237 and the one before is 1229.
- 3
The divisors add up to 1232; without 1231 itself that is 1, so 1231 is deficient (1 is less than 1231). Euler's totient φ(1231) = 1230 numbers up to 1231 share no factor with it.
- 4
The digits of 1231 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 70 steps to reach 1.
1231 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 1232 |
| Euler totient φ(n) | 1230 |
| Square | 1515361 |
| Cube | 1865409391 |
| Square root | 35.085610 |
| Digit sum / digital root | 7 / 7 |
| Collatz steps to 1 | 70 |
| Scientific notation | 1.231 × |
1231 in other forms
| Form | Value |
|---|---|
| In words | one thousand two hundred and thirty-one |
| Roman numerals | MCCXXXI |
| Binary (base 2) | 10011001111 |
| Octal (base 8) | 2317 |
| Hexadecimal (base 16) | 4CF |
| Base 3 | 1200121 |
| As time | 1231 seconds = 20 min 31 s |
Is 1231 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 3) | 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 7) | 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 10) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 1231 a prime number?
Yes. 1231 is divisible only by 1 and itself.
What are the factors of 1231?
1, 1231.
What is 1231 in binary?
10011001111 (hexadecimal 4CF, octal 2317).
What is the square root of 1231?
About 35.0856.
What is 1231 in Roman numerals?
MCCXXXI.
Is 1231 divisible by 3?
No. Its digits add up to 7, which is not a multiple of 3.
What is special about the number 1231?
1231 is a twin prime (1229 and 1231 are both prime); the 202nd prime number.