The number 20121
20121 is a composite number with 8 divisors. Its prime factorisation is 3 × 19 × 353. Divisors (8): 1, 3, 19, 57, 353, 1059, 6707, 20121.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 20121: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
20121 is composite. Its prime factorisation is
- 3
The divisors add up to 28320; without 20121 itself that is 8199, so 20121 is deficient (8199 is less than 20121). Euler's totient φ(20121) = 12672 numbers up to 20121 share no factor with it.
- 4
The digits of 20121 add up to 6, 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
\[ 20121 = 3 \times 19 \times 353 \]
20121 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 28320 |
| Euler totient φ(n) | 12672 |
| Square | 404854641 |
| Cube | 8146080231561 |
| Square root | 141.848511 |
| Digit sum / digital root | 6 / 6 |
| Collatz steps to 1 | 74 |
| Scientific notation | 2.0121 × |
20121 in other forms
| Form | Value |
|---|---|
| In words | twenty thousand one hundred and twenty-one |
| Binary (base 2) | 100111010011001 |
| Octal (base 8) | 47231 |
| Hexadecimal (base 16) | 4E99 |
| Base 3 | 1000121020 |
| As time | 20121 seconds = 5 h 35 min 21 s |
Is 20121 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 (20121 ÷ 3 = 6707) | 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 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 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 2) | 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 20121 a prime number?
No. 20121 = 3 × 19 × 353, so it is divisible by 3.
What are the factors of 20121?
1, 3, 19, 57, 353, 1059, 6707, 20121.
What is 20121 in binary?
100111010011001 (hexadecimal 4E99, octal 47231).
What is the square root of 20121?
About 141.8485.
Is 20121 divisible by 3?
Yes. Its digits add up to 6, a multiple of 3.
What is special about the number 20121?
20121 is a happy number: repeatedly adding the squares of its digits reaches 1.