The number 6643
6643 is a binary palindrome (1100111110011). Its prime factorisation is 7 × 13 × 73. Divisors (8): 1, 7, 13, 73, 91, 511, 949, 6643.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 6643: a binary palindrome (1100111110011); a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
6643 is composite. Its prime factorisation is
- 3
The divisors add up to 8288; without 6643 itself that is 1645, so 6643 is deficient (1645 is less than 6643). Euler's totient φ(6643) = 5184 numbers up to 6643 share no factor with it.
- 4
The digits of 6643 add up to 19, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 106 steps to reach 1.
LaTeX source of the formulas on this page
\[ 6643 = 7 \times 13 \times 73 \]
6643 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 8288 |
| Euler totient φ(n) | 5184 |
| Square | 44129449 |
| Cube | 293151929707 |
| Square root | 81.504601 |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 106 |
| Scientific notation | 6.643 × |
6643 in other forms
| Form | Value |
|---|---|
| In words | six thousand six hundred and forty-three |
| Binary (base 2) | 1100111110011 |
| Octal (base 8) | 14763 |
| Hexadecimal (base 16) | 19F3 |
| Base 3 | 100010001 |
| As time | 6643 seconds = 1 h 50 min 43 s |
Is 6643 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 | Yes (6643 ÷ 7 = 949) | 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 1) | 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 6643 a prime number?
No. 6643 = 7 × 13 × 73, so it is divisible by 7.
What are the factors of 6643?
1, 7, 13, 73, 91, 511, 949, 6643.
What is 6643 in binary?
1100111110011 (hexadecimal 19F3, octal 14763).
What is the square root of 6643?
About 81.5046.
Is 6643 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 6643?
6643 is a binary palindrome (1100111110011); a happy number: repeatedly adding the squares of its digits reaches 1.