The number 1668
1668 is a composite number with 12 divisors. Its prime factorisation is × 3 × 139. Divisors (12): 1, 2, 3, 4, 6, 12, 139, 278, 417, 556, 834, 1668.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
1668 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
1668 is composite. Its prime factorisation is
- 3
The divisors add up to 3920; without 1668 itself that is 2252, so 1668 is abundant (2252 is more than 1668). Euler's totient φ(1668) = 552 numbers up to 1668 share no factor with it.
- 4
The digits of 1668 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 135 steps to reach 1.
LaTeX source of the formulas on this page
\[ 1668 = 2^{2} \times 3 \times 139 \]1668 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 3920 |
| Euler totient φ(n) | 552 |
| Square | 2782224 |
| Cube | 4640749632 |
| Square root | 40.841156 (= 2√417) |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 135 |
| Scientific notation | 1.668 × |
1668 in other forms
| Form | Value |
|---|---|
| In words | one thousand six hundred and sixty-eight |
| Roman numerals | MDCLXVIII |
| Binary (base 2) | 11010000100 |
| Octal (base 8) | 3204 |
| Hexadecimal (base 16) | 684 |
| Base 3 | 2021210 |
| As time | 1668 seconds = 27 min 48 s |
Is 1668 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (1668 ÷ 2 = 834) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (1668 ÷ 3 = 556) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (1668 ÷ 4 = 417) | 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 | Yes (1668 ÷ 6 = 278) | 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 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | 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 7) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (1668 ÷ 12 = 139) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 1668 a prime number?
No. 1668 = × 3 × 139, so it is divisible by 2.
What are the factors of 1668?
1, 2, 3, 4, 6, 12, 139, 278, 417, 556, 834, 1668.
What is 1668 in binary?
11010000100 (hexadecimal 684, octal 3204).
What is the square root of 1668?
About 40.8412, exactly 2√417.
What is 1668 in Roman numerals?
MDCLXVIII.
Is 1668 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 1668?
It is a composite number with 12 divisors.