The number 989
989 is a palindrome: it reads 989 backwards too. Its prime factorisation is 23 × 43. Divisors (4): 1, 23, 43, 989.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 989: a palindrome: it reads 989 backwards too; a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 23 × 43, the product of two primes.
- 2
989 is composite. Its prime factorisation is
- 3
The divisors add up to 1056; without 989 itself that is 67, so 989 is deficient (67 is less than 989). Euler's totient φ(989) = 924 numbers up to 989 share no factor with it.
- 4
The digits of 989 add up to 26, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 49 steps to reach 1.
LaTeX source of the formulas on this page
\[ 989 = 23 \times 43 \]
989 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 1056 |
| Euler totient φ(n) | 924 |
| Square | 978121 |
| Cube | 967361669 |
| Square root | 31.448370 |
| Digit sum / digital root | 26 / 8 |
| Collatz steps to 1 | 49 |
| Scientific notation | 9.89 × |
989 in other forms
| Form | Value |
|---|---|
| In words | nine hundred and eighty-nine |
| Roman numerals | CMLXXXIX |
| Binary (base 2) | 1111011101 |
| Octal (base 8) | 1735 |
| Hexadecimal (base 16) | 3DD |
| Base 3 | 1100122 |
| As time | 989 seconds = 16 min 29 s |
Is 989 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 2) | 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 5) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 8) | 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 10) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 989 a prime number?
No. 989 = 23 × 43, so it is divisible by 23.
What are the factors of 989?
1, 23, 43, 989.
What is 989 in binary?
1111011101 (hexadecimal 3DD, octal 1735).
What is the square root of 989?
About 31.4484.
What is 989 in Roman numerals?
CMLXXXIX.
Is 989 divisible by 3?
No. Its digits add up to 26, which is not a multiple of 3.
What is special about the number 989?
989 is a palindrome: it reads 989 backwards too; a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 23 × 43, the product of two primes.