The number 21229
21229 is a composite number with 8 divisors. Its prime factorisation is 13 × 23 × 71. Divisors (8): 1, 13, 23, 71, 299, 923, 1633, 21229.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21229: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
21229 is composite. Its prime factorisation is
- 3
The divisors add up to 24192; without 21229 itself that is 2963, so 21229 is deficient (2963 is less than 21229). Euler's totient φ(21229) = 18480 numbers up to 21229 share no factor with it.
- 4
The digits of 21229 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 149 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21229 = 13 \times 23 \times 71 \]
21229 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 24192 |
| Euler totient φ(n) | 18480 |
| Square | 450670441 |
| Cube | 9567282791989 |
| Square root | 145.701750 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 149 |
| Scientific notation | 2.1229 × |
21229 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand two hundred and twenty-nine |
| Binary (base 2) | 101001011101101 |
| Octal (base 8) | 51355 |
| Hexadecimal (base 16) | 52ED |
| Base 3 | 1002010021 |
| As time | 21229 seconds = 5 h 53 min 49 s |
Is 21229 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 1) | 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 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 5) | 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 7) | 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 10) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21229 a prime number?
No. 21229 = 13 × 23 × 71, so it is divisible by 13.
What are the factors of 21229?
1, 13, 23, 71, 299, 923, 1633, 21229.
What is 21229 in binary?
101001011101101 (hexadecimal 52ED, octal 51355).
What is the square root of 21229?
About 145.7018.
Is 21229 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 21229?
21229 is a happy number: repeatedly adding the squares of its digits reaches 1.