The number 21507
21507 is a composite number with 8 divisors. Its prime factorisation is 3 × 67 × 107. Divisors (8): 1, 3, 67, 107, 201, 321, 7169, 21507.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21507: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
21507 is composite. Its prime factorisation is
- 3
The divisors add up to 29376; without 21507 itself that is 7869, so 21507 is deficient (7869 is less than 21507). Euler's totient φ(21507) = 13992 numbers up to 21507 share no factor with it.
- 4
The digits of 21507 add up to 15, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 74 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21507 = 3 \times 67 \times 107 \]
21507 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 29376 |
| Euler totient φ(n) | 13992 |
| Square | 462551049 |
| Cube | 9948085410843 |
| Square root | 146.652651 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 74 |
| Scientific notation | 2.1507 × |
21507 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand five hundred and seven |
| Binary (base 2) | 101010000000011 |
| Octal (base 8) | 52003 |
| Hexadecimal (base 16) | 5403 |
| Base 3 | 1002111120 |
| As time | 21507 seconds = 5 h 58 min 27 s |
Is 21507 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 (21507 ÷ 3 = 7169) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 2) | 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 3) | 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 6) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 7) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21507 a prime number?
No. 21507 = 3 × 67 × 107, so it is divisible by 3.
What are the factors of 21507?
1, 3, 67, 107, 201, 321, 7169, 21507.
What is 21507 in binary?
101010000000011 (hexadecimal 5403, octal 52003).
What is the square root of 21507?
About 146.6527.
Is 21507 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 21507?
21507 is a happy number: repeatedly adding the squares of its digits reaches 1.