The number 89
89 is a Fibonacci number and the 24th prime number. Its only divisors are 1 and 89.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 89: a Fibonacci number; the 24th prime number.
- 2
89 is prime, so its only factors are 1 and 89. It is the 24th prime; the next prime is 97 and the one before is 83.
- 3
The divisors add up to 90; without 89 itself that is 1, so 89 is deficient (1 is less than 89). Euler's totient φ(89) = 88 numbers up to 89 share no factor with it.
- 4
The digits of 89 add up to 17, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 30 steps to reach 1.
89 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 90 |
| Euler totient φ(n) | 88 |
| Square | 7921 |
| Cube | 704969 |
| Square root | 9.433981 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 30 |
| Scientific notation | 8.9 × |
89 in other forms
| Form | Value |
|---|---|
| In words | eighty-nine |
| Roman numerals | LXXXIX |
| Binary (base 2) | 1011001 |
| Octal (base 8) | 131 |
| Hexadecimal (base 16) | 59 |
| Base 3 | 10022 |
| As time | 89 seconds = 1 min 29 s |
Is 89 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 5) | 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 1) | 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 1) | 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 89 a prime number?
Yes. 89 is divisible only by 1 and itself.
What are the factors of 89?
1, 89.
What is 89 in binary?
1011001 (hexadecimal 59, octal 131).
What is the square root of 89?
About 9.4340.
What is 89 in Roman numerals?
LXXXIX.
Is 89 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 89?
89 is a Fibonacci number; the 24th prime number.