The number 19901
19901 is a composite number with 4 divisors. Its prime factorisation is 7 × 2843. Divisors (4): 1, 7, 2843, 19901.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 19901: a semiprime: 7 × 2843, the product of two primes.
- 2
19901 is composite. Its prime factorisation is
- 3
The divisors add up to 22752; without 19901 itself that is 2851, so 19901 is deficient (2851 is less than 19901). Euler's totient φ(19901) = 17052 numbers up to 19901 share no factor with it.
- 4
The digits of 19901 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
\[ 19901 = 7 \times 2843 \]
19901 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 22752 |
| Euler totient φ(n) | 17052 |
| Square | 396049801 |
| Cube | 7881787089701 |
| Square root | 141.070904 |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 74 |
| Scientific notation | 1.9901 × |
19901 in other forms
| Form | Value |
|---|---|
| In words | nineteen thousand nine hundred and one |
| Binary (base 2) | 100110110111101 |
| Octal (base 8) | 46675 |
| Hexadecimal (base 16) | 4DBD |
| Base 3 | 1000022002 |
| As time | 19901 seconds = 5 h 31 min 41 s |
Is 19901 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | 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 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (19901 ÷ 7 = 2843) | 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 5) | 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 | No (remainder 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 19901 a prime number?
No. 19901 = 7 × 2843, so it is divisible by 7.
What are the factors of 19901?
1, 7, 2843, 19901.
What is 19901 in binary?
100110110111101 (hexadecimal 4DBD, octal 46675).
What is the square root of 19901?
About 141.0709.
Is 19901 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 19901?
19901 is a semiprime: 7 × 2843, the product of two primes.