The number 12921
12921 is a palindrome: it reads 12921 backwards too. Its prime factorisation is 3 × 59 × 73. Divisors (8): 1, 3, 59, 73, 177, 219, 4307, 12921.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 12921: a palindrome: it reads 12921 backwards too; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
12921 is composite. Its prime factorisation is
- 3
The divisors add up to 17760; without 12921 itself that is 4839, so 12921 is deficient (4839 is less than 12921). Euler's totient φ(12921) = 8352 numbers up to 12921 share no factor with it.
- 4
The digits of 12921 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 63 steps to reach 1.
LaTeX source of the formulas on this page
\[ 12921 = 3 \times 59 \times 73 \]
12921 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 17760 |
| Euler totient φ(n) | 8352 |
| Square | 166952241 |
| Cube | 2157189905961 |
| Square root | 113.670577 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 63 |
| Scientific notation | 1.2921 × |
12921 in other forms
| Form | Value |
|---|---|
| In words | twelve thousand nine hundred and twenty-one |
| Binary (base 2) | 11001001111001 |
| Octal (base 8) | 31171 |
| Hexadecimal (base 16) | 3279 |
| Base 3 | 122201120 |
| As time | 12921 seconds = 3 h 35 min 21 s |
Is 12921 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 (12921 ÷ 3 = 4307) | 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 6) | 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 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 12921 a prime number?
No. 12921 = 3 × 59 × 73, so it is divisible by 3.
What are the factors of 12921?
1, 3, 59, 73, 177, 219, 4307, 12921.
What is 12921 in binary?
11001001111001 (hexadecimal 3279, octal 31171).
What is the square root of 12921?
About 113.6706.
Is 12921 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 12921?
12921 is a palindrome: it reads 12921 backwards too; a happy number: repeatedly adding the squares of its digits reaches 1.