The number 10721
10721 is a composite number with 4 divisors. Its prime factorisation is 71 × 151. Divisors (4): 1, 71, 151, 10721.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 10721: a semiprime: 71 × 151, the product of two primes.
- 2
10721 is composite. Its prime factorisation is
- 3
The divisors add up to 10944; without 10721 itself that is 223, so 10721 is deficient (223 is less than 10721). Euler's totient φ(10721) = 10500 numbers up to 10721 share no factor with it.
- 4
The digits of 10721 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 99 steps to reach 1.
LaTeX source of the formulas on this page
\[ 10721 = 71 \times 151 \]
10721 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 10944 |
| Euler totient φ(n) | 10500 |
| Square | 114939841 |
| Cube | 1232270035361 |
| Square root | 103.542262 |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 99 |
| Scientific notation | 1.0721 × |
10721 in other forms
| Form | Value |
|---|---|
| In words | ten thousand seven hundred and twenty-one |
| Binary (base 2) | 10100111100001 |
| Octal (base 8) | 24741 |
| Hexadecimal (base 16) | 29E1 |
| Base 3 | 112201002 |
| As time | 10721 seconds = 2 h 58 min 41 s |
Is 10721 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 | No (remainder 4) | 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 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 7) | 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 10721 a prime number?
No. 10721 = 71 × 151, so it is divisible by 71.
What are the factors of 10721?
1, 71, 151, 10721.
What is 10721 in binary?
10100111100001 (hexadecimal 29E1, octal 24741).
What is the square root of 10721?
About 103.5423.
Is 10721 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 10721?
10721 is a semiprime: 71 × 151, the product of two primes.