The number 1989
1989 is a composite number with 12 divisors. Its prime factorisation is × 13 × 17. Divisors (12): 1, 3, 9, 13, 17, 39, 51, 117, 153, 221, 663, 1989.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
1989 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
1989 is composite. Its prime factorisation is
- 3
The divisors add up to 3276; without 1989 itself that is 1287, so 1989 is deficient (1287 is less than 1989). Euler's totient φ(1989) = 1152 numbers up to 1989 share no factor with it.
- 4
The digits of 1989 add up to 27, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 24 steps to reach 1.
LaTeX source of the formulas on this page
\[ 1989 = 3^{2} \times 13 \times 17 \]1989 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 3276 |
| Euler totient φ(n) | 1152 |
| Square | 3956121 |
| Cube | 7868724669 |
| Square root | 44.598206 (= 3√221) |
| Digit sum / digital root | 27 / 9 |
| Collatz steps to 1 | 24 |
| Scientific notation | 1.989 × |
1989 in other forms
| Form | Value |
|---|---|
| In words | one thousand nine hundred and eighty-nine |
| Roman numerals | MCMLXXXIX |
| Binary (base 2) | 11111000101 |
| Octal (base 8) | 3705 |
| Hexadecimal (base 16) | 7C5 |
| Base 3 | 2201200 |
| As time | 1989 seconds = 33 min 9 s |
Is 1989 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 | Yes (1989 ÷ 3 = 663) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 4) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (1989 ÷ 9 = 221) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 9) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 1989 a prime number?
No. 1989 = × 13 × 17, so it is divisible by 3.
What are the factors of 1989?
1, 3, 9, 13, 17, 39, 51, 117, 153, 221, 663, 1989.
What is 1989 in binary?
11111000101 (hexadecimal 7C5, octal 3705).
What is the square root of 1989?
About 44.5982, exactly 3√221.
What is 1989 in Roman numerals?
MCMLXXXIX.
Is 1989 divisible by 3?
Yes. Its digits add up to 27, a multiple of 3.
What is special about the number 1989?
It is a composite number with 12 divisors.