The number 20729
20729 is a composite number with 4 divisors. Its prime factorisation is 19 × 1091. Divisors (4): 1, 19, 1091, 20729.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 20729: a semiprime: 19 × 1091, the product of two primes.
- 2
20729 is composite. Its prime factorisation is
- 3
The divisors add up to 21840; without 20729 itself that is 1111, so 20729 is deficient (1111 is less than 20729). Euler's totient φ(20729) = 19620 numbers up to 20729 share no factor with it.
- 4
The digits of 20729 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 61 steps to reach 1.
LaTeX source of the formulas on this page
\[ 20729 = 19 \times 1091 \]
20729 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 21840 |
| Euler totient φ(n) | 19620 |
| Square | 429691441 |
| Cube | 8907073880489 |
| Square root | 143.975692 |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 61 |
| Scientific notation | 2.0729 × |
20729 in other forms
| Form | Value |
|---|---|
| In words | twenty thousand seven hundred and twenty-nine |
| Binary (base 2) | 101000011111001 |
| Octal (base 8) | 50371 |
| Hexadecimal (base 16) | 50F9 |
| Base 3 | 1001102202 |
| As time | 20729 seconds = 5 h 45 min 29 s |
Is 20729 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 4) | 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 2) | 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 9) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | 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 20729 a prime number?
No. 20729 = 19 × 1091, so it is divisible by 19.
What are the factors of 20729?
1, 19, 1091, 20729.
What is 20729 in binary?
101000011111001 (hexadecimal 50F9, octal 50371).
What is the square root of 20729?
About 143.9757.
Is 20729 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 20729?
20729 is a semiprime: 19 × 1091, the product of two primes.