The number 19820
19820 is a composite number with 12 divisors. Its prime factorisation is × 5 × 991. Divisors (12): 1, 2, 4, 5, 10, 20, 991, 1982, 3964, 4955, 9910, 19820.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 19820: a Harshad number: divisible by its digit sum 20.
- 2
19820 is composite. Its prime factorisation is
- 3
The divisors add up to 41664; without 19820 itself that is 21844, so 19820 is abundant (21844 is more than 19820). Euler's totient φ(19820) = 7920 numbers up to 19820 share no factor with it.
- 4
The digits of 19820 add up to 20, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 74 steps to reach 1.
LaTeX source of the formulas on this page
\[ 19820 = 2^{2} \times 5 \times 991 \]19820 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 41664 |
| Euler totient φ(n) | 7920 |
| Square | 392832400 |
| Cube | 7785938168000 |
| Square root | 140.783522 (= 2√4955) |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 74 |
| Scientific notation | 1.982 × |
19820 in other forms
| Form | Value |
|---|---|
| In words | nineteen thousand eight hundred and twenty |
| Binary (base 2) | 100110101101100 |
| Octal (base 8) | 46554 |
| Hexadecimal (base 16) | 4D6C |
| Base 3 | 1000012002 |
| As time | 19820 seconds = 5 h 30 min 20 s |
Is 19820 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (19820 ÷ 2 = 9910) | 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 | Yes (19820 ÷ 4 = 4955) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (19820 ÷ 5 = 3964) | 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 3) | 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 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 2) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (19820 ÷ 10 = 1982) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 19820 a prime number?
No. 19820 = × 5 × 991, so it is divisible by 2.
What are the factors of 19820?
1, 2, 4, 5, 10, 20, 991, 1982, 3964, 4955, 9910, 19820.
What is 19820 in binary?
100110101101100 (hexadecimal 4D6C, octal 46554).
What is the square root of 19820?
About 140.7835, exactly 2√4955.
Is 19820 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 19820?
19820 is a Harshad number: divisible by its digit sum 20.