The number 197
197 is a twin prime (197 and 199 are both prime) and the 45th prime number. Its only divisors are 1 and 197.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 197: a twin prime (197 and 199 are both prime); the 45th prime number.
- 2
197 is prime, so its only factors are 1 and 197. It is the 45th prime; the next prime is 199 and the one before is 193.
- 3
The divisors add up to 198; without 197 itself that is 1, so 197 is deficient (1 is less than 197). Euler's totient φ(197) = 196 numbers up to 197 share no factor with it.
- 4
The digits of 197 add up to 17, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 26 steps to reach 1.
197 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 198 |
| Euler totient φ(n) | 196 |
| Square | 38809 |
| Cube | 7645373 |
| Square root | 14.035669 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 26 |
| Scientific notation | 1.97 × |
197 in other forms
| Form | Value |
|---|---|
| In words | one hundred and ninety-seven |
| Roman numerals | CXCVII |
| Binary (base 2) | 11000101 |
| Octal (base 8) | 305 |
| Hexadecimal (base 16) | C5 |
| Base 3 | 21022 |
| As time | 197 seconds = 3 min 17 s |
Is 197 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 2) | 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 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 5) | 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 7) | 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 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 197 a prime number?
Yes. 197 is divisible only by 1 and itself.
What are the factors of 197?
1, 197.
What is 197 in binary?
11000101 (hexadecimal C5, octal 305).
What is the square root of 197?
About 14.0357.
What is 197 in Roman numerals?
CXCVII.
Is 197 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 197?
197 is a twin prime (197 and 199 are both prime); the 45th prime number.