The number 668
668 is a composite number with 6 divisors. Its prime factorisation is × 167. Divisors (6): 1, 2, 4, 167, 334, 668.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
668 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
668 is composite. Its prime factorisation is
- 3
The divisors add up to 1176; without 668 itself that is 508, so 668 is deficient (508 is less than 668). Euler's totient φ(668) = 332 numbers up to 668 share no factor with it.
- 4
The digits of 668 add up to 20, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 69 steps to reach 1.
LaTeX source of the formulas on this page
\[ 668 = 2^{2} \times 167 \]668 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 1176 |
| Euler totient φ(n) | 332 |
| Square | 446224 |
| Cube | 298077632 |
| Square root | 25.845696 (= 2√167) |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 69 |
| Scientific notation | 6.68 × |
668 in other forms
| Form | Value |
|---|---|
| In words | six hundred and sixty-eight |
| Roman numerals | DCLXVIII |
| Binary (base 2) | 1010011100 |
| Octal (base 8) | 1234 |
| Hexadecimal (base 16) | 29C |
| Base 3 | 220202 |
| As time | 668 seconds = 11 min 8 s |
Is 668 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (668 ÷ 2 = 334) | 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 | Yes (668 ÷ 4 = 167) | 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 2) | 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 4) | 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 8) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 8) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 668 a prime number?
No. 668 = × 167, so it is divisible by 2.
What are the factors of 668?
1, 2, 4, 167, 334, 668.
What is 668 in binary?
1010011100 (hexadecimal 29C, octal 1234).
What is the square root of 668?
About 25.8457, exactly 2√167.
What is 668 in Roman numerals?
DCLXVIII.
Is 668 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 668?
It is a composite number with 6 divisors.