The number 1666
1666 is a composite number with 12 divisors. Its prime factorisation is 2 × × 17. Divisors (12): 1, 2, 7, 14, 17, 34, 49, 98, 119, 238, 833, 1666.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 1666: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
1666 is composite. Its prime factorisation is
- 3
The divisors add up to 3078; without 1666 itself that is 1412, so 1666 is deficient (1412 is less than 1666). Euler's totient φ(1666) = 672 numbers up to 1666 share no factor with it.
- 4
The digits of 1666 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 29 steps to reach 1.
LaTeX source of the formulas on this page
\[ 1666 = 2 \times 7^{2} \times 17 \]1666 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 3078 |
| Euler totient φ(n) | 672 |
| Square | 2775556 |
| Cube | 4624076296 |
| Square root | 40.816663 (= 7√34) |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 29 |
| Scientific notation | 1.666 × |
1666 in other forms
| Form | Value |
|---|---|
| In words | one thousand six hundred and sixty-six |
| Roman numerals | MDCLXVI |
| Binary (base 2) | 11010000010 |
| Octal (base 8) | 3202 |
| Hexadecimal (base 16) | 682 |
| Base 3 | 2021201 |
| As time | 1666 seconds = 27 min 46 s |
Is 1666 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (1666 ÷ 2 = 833) | 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 2) | 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 4) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (1666 ÷ 7 = 238) | 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 2) | 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 6) | 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 10) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 1666 a prime number?
No. 1666 = 2 × × 17, so it is divisible by 2.
What are the factors of 1666?
1, 2, 7, 14, 17, 34, 49, 98, 119, 238, 833, 1666.
What is 1666 in binary?
11010000010 (hexadecimal 682, octal 3202).
What is the square root of 1666?
About 40.8167, exactly 7√34.
What is 1666 in Roman numerals?
MDCLXVI.
Is 1666 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 1666?
1666 is a happy number: repeatedly adding the squares of its digits reaches 1.