The number 28101
28101 is a composite number with 16 divisors. Its prime factorisation is 3 × 17 × 19 × 29. Divisors (16): 1, 3, 17, 19, 29, 51, 57, 87, 323, 493, 551, 969, 1479, 1653, 9367, 28101.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 28101: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
28101 is composite. Its prime factorisation is
- 3
The divisors add up to 43200; without 28101 itself that is 15099, so 28101 is deficient (15099 is less than 28101). Euler's totient φ(28101) = 16128 numbers up to 28101 share no factor with it.
- 4
The digits of 28101 add up to 12, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 59 steps to reach 1.
LaTeX source of the formulas on this page
\[ 28101 = 3 \times 17 \times 19 \times 29 \]
28101 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 43200 |
| Euler totient φ(n) | 16128 |
| Square | 789666201 |
| Cube | 22190409914301 |
| Square root | 167.633529 |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 59 |
| Scientific notation | 2.8101 × |
28101 in other forms
| Form | Value |
|---|---|
| In words | twenty-eight thousand one hundred and one |
| Binary (base 2) | 110110111000101 |
| Octal (base 8) | 66705 |
| Hexadecimal (base 16) | 6DC5 |
| Base 3 | 1102112210 |
| As time | 28101 seconds = 7 h 48 min 21 s |
Is 28101 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 (28101 ÷ 3 = 9367) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | 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 28101 a prime number?
No. 28101 = 3 × 17 × 19 × 29, so it is divisible by 3.
What are the factors of 28101?
1, 3, 17, 19, 29, 51, 57, 87, 323, 493, 551, 969, 1479, 1653, 9367, 28101.
What is 28101 in binary?
110110111000101 (hexadecimal 6DC5, octal 66705).
What is the square root of 28101?
About 167.6335.
Is 28101 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 28101?
28101 is a happy number: repeatedly adding the squares of its digits reaches 1.