The number 21029
21029 is a binary palindrome (101001000100101). Its prime factorisation is 17 × 1237. Divisors (4): 1, 17, 1237, 21029.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21029: a binary palindrome (101001000100101); a semiprime: 17 × 1237, the product of two primes.
- 2
21029 is composite. Its prime factorisation is
- 3
The divisors add up to 22284; without 21029 itself that is 1255, so 21029 is deficient (1255 is less than 21029). Euler's totient φ(21029) = 19776 numbers up to 21029 share no factor with it.
- 4
The digits of 21029 add up to 14, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 180 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21029 = 17 \times 1237 \]
21029 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 22284 |
| Euler totient φ(n) | 19776 |
| Square | 442218841 |
| Cube | 9299420007389 |
| Square root | 145.013792 |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 180 |
| Scientific notation | 2.1029 × |
21029 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand and twenty-nine |
| Binary (base 2) | 101001000100101 |
| Octal (base 8) | 51045 |
| Hexadecimal (base 16) | 5225 |
| Base 3 | 1001211212 |
| As time | 21029 seconds = 5 h 50 min 29 s |
Is 21029 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 1) | 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 5) | 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 8) | 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 21029 a prime number?
No. 21029 = 17 × 1237, so it is divisible by 17.
What are the factors of 21029?
1, 17, 1237, 21029.
What is 21029 in binary?
101001000100101 (hexadecimal 5225, octal 51045).
What is the square root of 21029?
About 145.0138.
Is 21029 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 21029?
21029 is a binary palindrome (101001000100101); a semiprime: 17 × 1237, the product of two primes.