The number 81998
81998 is a composite number with 8 divisors. Its prime factorisation is 2 × 7 × 5857. Divisors (8): 1, 2, 7, 14, 5857, 11714, 40999, 81998.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 81998: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
81998 is composite. Its prime factorisation is
- 3
The divisors add up to 140592; without 81998 itself that is 58594, so 81998 is deficient (58594 is less than 81998). Euler's totient φ(81998) = 35136 numbers up to 81998 share no factor with it.
- 4
The digits of 81998 add up to 35, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 182 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81998 = 2 \times 7 \times 5857 \]
81998 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 140592 |
| Euler totient φ(n) | 35136 |
| Square | 6723672004 |
| Cube | 551327656983992 |
| Square root | 286.352929 |
| Digit sum / digital root | 35 / 8 |
| Collatz steps to 1 | 182 |
| Scientific notation | 8.1998 × |
81998 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand nine hundred and ninety-eight |
| Binary (base 2) | 10100000001001110 |
| Octal (base 8) | 240116 |
| Hexadecimal (base 16) | 1404E |
| Base 3 | 11011110222 |
| As time | 81998 seconds = 22 h 46 min 38 s |
Is 81998 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (81998 ÷ 2 = 40999) | 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 | Yes (81998 ÷ 7 = 11714) | 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 4) | 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 81998 a prime number?
No. 81998 = 2 × 7 × 5857, so it is divisible by 2.
What are the factors of 81998?
1, 2, 7, 14, 5857, 11714, 40999, 81998.
What is 81998 in binary?
10100000001001110 (hexadecimal 1404E, octal 240116).
What is the square root of 81998?
About 286.3529.
Is 81998 divisible by 3?
No. Its digits add up to 35, which is not a multiple of 3.
What is special about the number 81998?
81998 is a happy number: repeatedly adding the squares of its digits reaches 1.