The number 19221
19221 is a composite number with 8 divisors. Its prime factorisation is 3 × 43 × 149. Divisors (8): 1, 3, 43, 129, 149, 447, 6407, 19221.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 19221: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
19221 is composite. Its prime factorisation is
- 3
The divisors add up to 26400; without 19221 itself that is 7179, so 19221 is deficient (7179 is less than 19221). Euler's totient φ(19221) = 12432 numbers up to 19221 share no factor with it.
- 4
The digits of 19221 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 61 steps to reach 1.
LaTeX source of the formulas on this page
\[ 19221 = 3 \times 43 \times 149 \]
19221 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 26400 |
| Euler totient φ(n) | 12432 |
| Square | 369446841 |
| Cube | 7101137730861 |
| Square root | 138.639821 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 61 |
| Scientific notation | 1.9221 × |
19221 in other forms
| Form | Value |
|---|---|
| In words | nineteen thousand two hundred and twenty-one |
| Binary (base 2) | 100101100010101 |
| Octal (base 8) | 45425 |
| Hexadecimal (base 16) | 4B15 |
| Base 3 | 222100220 |
| As time | 19221 seconds = 5 h 20 min 21 s |
Is 19221 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 (19221 ÷ 3 = 6407) | 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 5) | 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 4) | 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 19221 a prime number?
No. 19221 = 3 × 43 × 149, so it is divisible by 3.
What are the factors of 19221?
1, 3, 43, 129, 149, 447, 6407, 19221.
What is 19221 in binary?
100101100010101 (hexadecimal 4B15, octal 45425).
What is the square root of 19221?
About 138.6398.
Is 19221 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 19221?
19221 is a happy number: repeatedly adding the squares of its digits reaches 1.