The number 731
731 is a composite number with 4 divisors. Its prime factorisation is 17 × 43. Divisors (4): 1, 17, 43, 731.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 731: a semiprime: 17 × 43, the product of two primes.
- 2
731 is composite. Its prime factorisation is
- 3
The divisors add up to 792; without 731 itself that is 61, so 731 is deficient (61 is less than 731). Euler's totient φ(731) = 672 numbers up to 731 share no factor with it.
- 4
The digits of 731 add up to 11, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 139 steps to reach 1.
LaTeX source of the formulas on this page
\[ 731 = 17 \times 43 \]
731 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 792 |
| Euler totient φ(n) | 672 |
| Square | 534361 |
| Cube | 390617891 |
| Square root | 27.037012 |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 139 |
| Scientific notation | 7.31 × |
731 in other forms
| Form | Value |
|---|---|
| In words | seven hundred and thirty-one |
| Roman numerals | DCCXXXI |
| Binary (base 2) | 1011011011 |
| Octal (base 8) | 1333 |
| Hexadecimal (base 16) | 2DB |
| Base 3 | 1000002 |
| As time | 731 seconds = 12 min 11 s |
Is 731 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 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 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 3) | 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 2) | 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 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 731 a prime number?
No. 731 = 17 × 43, so it is divisible by 17.
What are the factors of 731?
1, 17, 43, 731.
What is 731 in binary?
1011011011 (hexadecimal 2DB, octal 1333).
What is the square root of 731?
About 27.0370.
What is 731 in Roman numerals?
DCCXXXI.
Is 731 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 731?
731 is a semiprime: 17 × 43, the product of two primes.