The number 20998
20998 is a composite number with 4 divisors. Its prime factorisation is 2 × 10499. Divisors (4): 1, 2, 10499, 20998.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 20998: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 2 × 10499, the product of two primes.
- 2
20998 is composite. Its prime factorisation is
- 3
The divisors add up to 31500; without 20998 itself that is 10502, so 20998 is deficient (10502 is less than 20998). Euler's totient φ(20998) = 10498 numbers up to 20998 share no factor with it.
- 4
The digits of 20998 add up to 28, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 131 steps to reach 1.
LaTeX source of the formulas on this page
\[ 20998 = 2 \times 10499 \]
20998 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 31500 |
| Euler totient φ(n) | 10498 |
| Square | 440916004 |
| Cube | 9258354251992 |
| Square root | 144.906867 |
| Digit sum / digital root | 28 / 1 |
| Collatz steps to 1 | 131 |
| Scientific notation | 2.0998 × |
20998 in other forms
| Form | Value |
|---|---|
| In words | twenty thousand nine hundred and ninety-eight |
| Binary (base 2) | 101001000000110 |
| Octal (base 8) | 51006 |
| Hexadecimal (base 16) | 5206 |
| Base 3 | 1001210201 |
| As time | 20998 seconds = 5 h 49 min 58 s |
Is 20998 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (20998 ÷ 2 = 10499) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 1) | 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 4) | 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 6) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 1) | 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 10) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 10) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 20998 a prime number?
No. 20998 = 2 × 10499, so it is divisible by 2.
What are the factors of 20998?
1, 2, 10499, 20998.
What is 20998 in binary?
101001000000110 (hexadecimal 5206, octal 51006).
What is the square root of 20998?
About 144.9069.
Is 20998 divisible by 3?
No. Its digits add up to 28, which is not a multiple of 3.
What is special about the number 20998?
20998 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 2 × 10499, the product of two primes.