The number 43
43 is a twin prime (41 and 43 are both prime) and the 14th prime number. Its only divisors are 1 and 43.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 43: a twin prime (41 and 43 are both prime); the 14th prime number.
- 2
43 is prime, so its only factors are 1 and 43. It is the 14th prime; the next prime is 47 and the one before is 41.
- 3
The divisors add up to 44; without 43 itself that is 1, so 43 is deficient (1 is less than 43). Euler's totient φ(43) = 42 numbers up to 43 share no factor with it.
- 4
The digits of 43 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 29 steps to reach 1.
43 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 44 |
| Euler totient φ(n) | 42 |
| Square | 1849 |
| Cube | 79507 |
| Square root | 6.557439 |
| Digit sum / digital root | 7 / 7 |
| Collatz steps to 1 | 29 |
| Scientific notation | 4.3 × |
43 in other forms
| Form | Value |
|---|---|
| In words | forty-three |
| Roman numerals | XLIII |
| Binary (base 2) | 101011 |
| Octal (base 8) | 53 |
| Hexadecimal (base 16) | 2B |
| Base 3 | 1121 |
| As time | 43 seconds |
Is 43 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 3) | 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 3) | 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 3) | 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 43 a prime number?
Yes. 43 is divisible only by 1 and itself.
What are the factors of 43?
1, 43.
What is 43 in binary?
101011 (hexadecimal 2B, octal 53).
What is the square root of 43?
About 6.5574.
What is 43 in Roman numerals?
XLIII.
Is 43 divisible by 3?
No. Its digits add up to 7, which is not a multiple of 3.
What is special about the number 43?
43 is a twin prime (41 and 43 are both prime); the 14th prime number.