The number 21077
21077 is a composite number with 4 divisors. Its prime factorisation is 7 × 3011. Divisors (4): 1, 7, 3011, 21077.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21077: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 7 × 3011, the product of two primes.
- 2
21077 is composite. Its prime factorisation is
- 3
The divisors add up to 24096; without 21077 itself that is 3019, so 21077 is deficient (3019 is less than 21077). Euler's totient φ(21077) = 18060 numbers up to 21077 share no factor with it.
- 4
The digits of 21077 add up to 17, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 56 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21077 = 7 \times 3011 \]
21077 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 24096 |
| Euler totient φ(n) | 18060 |
| Square | 444239929 |
| Cube | 9363244983533 |
| Square root | 145.179200 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.1077 × |
21077 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand and seventy-seven |
| Binary (base 2) | 101001001010101 |
| Octal (base 8) | 51125 |
| Hexadecimal (base 16) | 5255 |
| Base 3 | 1001220122 |
| As time | 21077 seconds = 5 h 51 min 17 s |
Is 21077 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 2) | 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 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (21077 ÷ 7 = 3011) | 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 8) | 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 1) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21077 a prime number?
No. 21077 = 7 × 3011, so it is divisible by 7.
What are the factors of 21077?
1, 7, 3011, 21077.
What is 21077 in binary?
101001001010101 (hexadecimal 5255, octal 51125).
What is the square root of 21077?
About 145.1792.
Is 21077 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 21077?
21077 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 7 × 3011, the product of two primes.