The number 631
631 is the 115th prime number. Its only divisors are 1 and 631.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 631: the 115th prime number.
- 2
631 is prime, so its only factors are 1 and 631. It is the 115th prime; the next prime is 641 and the one before is 619.
- 3
The divisors add up to 632; without 631 itself that is 1, so 631 is deficient (1 is less than 631). Euler's totient φ(631) = 630 numbers up to 631 share no factor with it.
- 4
The digits of 631 add up to 10, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 38 steps to reach 1.
631 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 632 |
| Euler totient φ(n) | 630 |
| Square | 398161 |
| Cube | 251239591 |
| Square root | 25.119713 |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 38 |
| Scientific notation | 6.31 × |
631 in other forms
| Form | Value |
|---|---|
| In words | six hundred and thirty-one |
| Roman numerals | DCXXXI |
| Binary (base 2) | 1001110111 |
| Octal (base 8) | 1167 |
| Hexadecimal (base 16) | 277 |
| Base 3 | 212101 |
| As time | 631 seconds = 10 min 31 s |
Is 631 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 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 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 1) | 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 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 631 a prime number?
Yes. 631 is divisible only by 1 and itself.
What are the factors of 631?
1, 631.
What is 631 in binary?
1001110111 (hexadecimal 277, octal 1167).
What is the square root of 631?
About 25.1197.
What is 631 in Roman numerals?
DCXXXI.
Is 631 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 631?
631 is the 115th prime number.