The number 998
998 is a composite number with 4 divisors. Its prime factorisation is 2 × 499. Divisors (4): 1, 2, 499, 998.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 998: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 2 × 499, the product of two primes.
- 2
998 is composite. Its prime factorisation is
- 3
The divisors add up to 1500; without 998 itself that is 502, so 998 is deficient (502 is less than 998). Euler's totient φ(998) = 498 numbers up to 998 share no factor with it.
- 4
The digits of 998 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
\[ 998 = 2 \times 499 \]
998 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 1500 |
| Euler totient φ(n) | 498 |
| Square | 996004 |
| Cube | 994011992 |
| Square root | 31.591138 |
| Digit sum / digital root | 26 / 8 |
| Collatz steps to 1 | 49 |
| Scientific notation | 9.98 × |
998 in other forms
| Form | Value |
|---|---|
| In words | nine hundred and ninety-eight |
| Roman numerals | CMXCVIII |
| Binary (base 2) | 1111100110 |
| Octal (base 8) | 1746 |
| Hexadecimal (base 16) | 3E6 |
| Base 3 | 1100222 |
| As time | 998 seconds = 16 min 38 s |
Is 998 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (998 ÷ 2 = 499) | 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 2) | 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 | No (remainder 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 4) | 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 6) | 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 8) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 8) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 2) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 998 a prime number?
No. 998 = 2 × 499, so it is divisible by 2.
What are the factors of 998?
1, 2, 499, 998.
What is 998 in binary?
1111100110 (hexadecimal 3E6, octal 1746).
What is the square root of 998?
About 31.5911.
What is 998 in Roman numerals?
CMXCVIII.
Is 998 divisible by 3?
No. Its digits add up to 26, which is not a multiple of 3.
What is special about the number 998?
998 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 2 × 499, the product of two primes.