The number 247
247 is a composite number with 4 divisors. Its prime factorisation is 13 × 19. Divisors (4): 1, 13, 19, 247.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 247: a Harshad number: divisible by its digit sum 13; a semiprime: 13 × 19, the product of two primes.
- 2
247 is composite. Its prime factorisation is
- 3
The divisors add up to 280; without 247 itself that is 33, so 247 is deficient (33 is less than 247). Euler's totient φ(247) = 216 numbers up to 247 share no factor with it.
- 4
The digits of 247 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 47 steps to reach 1.
LaTeX source of the formulas on this page
\[ 247 = 13 \times 19 \]
247 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 280 |
| Euler totient φ(n) | 216 |
| Square | 61009 |
| Cube | 15069223 |
| Square root | 15.716234 |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 47 |
| Scientific notation | 2.47 × |
247 in other forms
| Form | Value |
|---|---|
| In words | two hundred and forty-seven |
| Roman numerals | CCXLVII |
| Binary (base 2) | 11110111 |
| Octal (base 8) | 367 |
| Hexadecimal (base 16) | F7 |
| Base 3 | 100011 |
| As time | 247 seconds = 4 min 7 s |
Is 247 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 2) | 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 2) | 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 4) | 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 5) | 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 247 a prime number?
No. 247 = 13 × 19, so it is divisible by 13.
What are the factors of 247?
1, 13, 19, 247.
What is 247 in binary?
11110111 (hexadecimal F7, octal 367).
What is the square root of 247?
About 15.7162.
What is 247 in Roman numerals?
CCXLVII.
Is 247 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 247?
247 is a Harshad number: divisible by its digit sum 13; a semiprime: 13 × 19, the product of two primes.