The number 19990
19990 is a composite number with 8 divisors. Its prime factorisation is 2 × 5 × 1999. Divisors (8): 1, 2, 5, 10, 1999, 3998, 9995, 19990.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
19990 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
19990 is composite. Its prime factorisation is
- 3
The divisors add up to 36000; without 19990 itself that is 16010, so 19990 is deficient (16010 is less than 19990). Euler's totient φ(19990) = 7992 numbers up to 19990 share no factor with it.
- 4
The digits of 19990 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 66 steps to reach 1.
LaTeX source of the formulas on this page
\[ 19990 = 2 \times 5 \times 1999 \]
19990 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 36000 |
| Euler totient φ(n) | 7992 |
| Square | 399600100 |
| Cube | 7988005999000 |
| Square root | 141.385996 |
| Digit sum / digital root | 28 / 1 |
| Collatz steps to 1 | 66 |
| Scientific notation | 1.999 × |
19990 in other forms
| Form | Value |
|---|---|
| In words | nineteen thousand nine hundred and ninety |
| Binary (base 2) | 100111000010110 |
| Octal (base 8) | 47026 |
| Hexadecimal (base 16) | 4E16 |
| Base 3 | 1000102101 |
| As time | 19990 seconds = 5 h 33 min 10 s |
Is 19990 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (19990 ÷ 2 = 9995) | 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 | Yes (19990 ÷ 5 = 3998) | 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 | Yes (19990 ÷ 10 = 1999) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 3) | 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 19990 a prime number?
No. 19990 = 2 × 5 × 1999, so it is divisible by 2.
What are the factors of 19990?
1, 2, 5, 10, 1999, 3998, 9995, 19990.
What is 19990 in binary?
100111000010110 (hexadecimal 4E16, octal 47026).
What is the square root of 19990?
About 141.3860.
Is 19990 divisible by 3?
No. Its digits add up to 28, which is not a multiple of 3.
What is special about the number 19990?
It is a composite number with 8 divisors.