The number 21877
21877 is a composite number with 4 divisors. Its prime factorisation is 131 × 167. Divisors (4): 1, 131, 167, 21877.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21877: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 131 × 167, the product of two primes.
- 2
21877 is composite. Its prime factorisation is
- 3
The divisors add up to 22176; without 21877 itself that is 299, so 21877 is deficient (299 is less than 21877). Euler's totient φ(21877) = 21580 numbers up to 21877 share no factor with it.
- 4
The digits of 21877 add up to 25, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 43 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21877 = 131 \times 167 \]
21877 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 22176 |
| Euler totient φ(n) | 21580 |
| Square | 478603129 |
| Cube | 10470400653133 |
| Square root | 147.908756 |
| Digit sum / digital root | 25 / 7 |
| Collatz steps to 1 | 43 |
| Scientific notation | 2.1877 × |
21877 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand eight hundred and seventy-seven |
| Binary (base 2) | 101010101110101 |
| Octal (base 8) | 52565 |
| Hexadecimal (base 16) | 5575 |
| Base 3 | 1010000021 |
| As time | 21877 seconds = 6 h 4 min 37 s |
Is 21877 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 | No (remainder 1) | 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 2) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 2) | 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 7) | 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 9) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21877 a prime number?
No. 21877 = 131 × 167, so it is divisible by 131.
What are the factors of 21877?
1, 131, 167, 21877.
What is 21877 in binary?
101010101110101 (hexadecimal 5575, octal 52565).
What is the square root of 21877?
About 147.9088.
Is 21877 divisible by 3?
No. Its digits add up to 25, which is not a multiple of 3.
What is special about the number 21877?
21877 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 131 × 167, the product of two primes.