The number 20513
20513 is a composite number with 4 divisors. Its prime factorisation is 73 × 281. Divisors (4): 1, 73, 281, 20513.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 20513: a semiprime: 73 × 281, the product of two primes.
- 2
20513 is composite. Its prime factorisation is
- 3
The divisors add up to 20868; without 20513 itself that is 355, so 20513 is deficient (355 is less than 20513). Euler's totient φ(20513) = 20160 numbers up to 20513 share no factor with it.
- 4
The digits of 20513 add up to 11, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 180 steps to reach 1.
LaTeX source of the formulas on this page
\[ 20513 = 73 \times 281 \]
20513 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 20868 |
| Euler totient φ(n) | 20160 |
| Square | 420783169 |
| Cube | 8631525145697 |
| Square root | 143.223601 |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 180 |
| Scientific notation | 2.0513 × |
20513 in other forms
| Form | Value |
|---|---|
| In words | twenty thousand five hundred and thirteen |
| Binary (base 2) | 101000000100001 |
| Octal (base 8) | 50041 |
| Hexadecimal (base 16) | 5021 |
| Base 3 | 1001010202 |
| As time | 20513 seconds = 5 h 41 min 53 s |
Is 20513 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 3) | 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 | 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 1) | 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 3) | 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 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 20513 a prime number?
No. 20513 = 73 × 281, so it is divisible by 73.
What are the factors of 20513?
1, 73, 281, 20513.
What is 20513 in binary?
101000000100001 (hexadecimal 5021, octal 50041).
What is the square root of 20513?
About 143.2236.
Is 20513 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 20513?
20513 is a semiprime: 73 × 281, the product of two primes.