The number 29721
29721 is a composite number with 4 divisors. Its prime factorisation is 3 × 9907. Divisors (4): 1, 3, 9907, 29721.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 29721: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 3 × 9907, the product of two primes.
- 2
29721 is composite. Its prime factorisation is
- 3
The divisors add up to 39632; without 29721 itself that is 9911, so 29721 is deficient (9911 is less than 29721). Euler's totient φ(29721) = 19812 numbers up to 29721 share no factor with it.
- 4
The digits of 29721 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 147 steps to reach 1.
LaTeX source of the formulas on this page
\[ 29721 = 3 \times 9907 \]
29721 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 39632 |
| Euler totient φ(n) | 19812 |
| Square | 883337841 |
| Cube | 26253683972361 |
| Square root | 172.397796 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 147 |
| Scientific notation | 2.9721 × |
29721 in other forms
| Form | Value |
|---|---|
| In words | twenty-nine thousand seven hundred and twenty-one |
| Binary (base 2) | 111010000011001 |
| Octal (base 8) | 72031 |
| Hexadecimal (base 16) | 7419 |
| Base 3 | 1111202210 |
| As time | 29721 seconds = 8 h 15 min 21 s |
Is 29721 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 | Yes (29721 ÷ 3 = 9907) | 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 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 6) | 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 3) | 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 10) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 29721 a prime number?
No. 29721 = 3 × 9907, so it is divisible by 3.
What are the factors of 29721?
1, 3, 9907, 29721.
What is 29721 in binary?
111010000011001 (hexadecimal 7419, octal 72031).
What is the square root of 29721?
About 172.3978.
Is 29721 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 29721?
29721 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 3 × 9907, the product of two primes.