The number 77021
77021 is a composite number with 4 divisors. Its prime factorisation is 7 × 11003. Divisors (4): 1, 7, 11003, 77021.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 77021: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 7 × 11003, the product of two primes.
- 2
77021 is composite. Its prime factorisation is
- 3
The divisors add up to 88032; without 77021 itself that is 11011, so 77021 is deficient (11011 is less than 77021). Euler's totient φ(77021) = 66012 numbers up to 77021 share no factor with it.
- 4
The digits of 77021 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 50 steps to reach 1.
LaTeX source of the formulas on this page
\[ 77021 = 7 \times 11003 \]
77021 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 88032 |
| Euler totient φ(n) | 66012 |
| Square | 5932234441 |
| Cube | 456906628880261 |
| Square root | 277.526575 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 50 |
| Scientific notation | 7.7021 × |
77021 in other forms
| Form | Value |
|---|---|
| In words | seventy-seven thousand and twenty-one |
| Binary (base 2) | 10010110011011101 |
| Octal (base 8) | 226335 |
| Hexadecimal (base 16) | 12CDD |
| Base 3 | 10220122122 |
| As time | 77021 seconds = 21 h 23 min 41 s |
Is 77021 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 1) | 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 (77021 ÷ 7 = 11003) | 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 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 10) | 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 77021 a prime number?
No. 77021 = 7 × 11003, so it is divisible by 7.
What are the factors of 77021?
1, 7, 11003, 77021.
What is 77021 in binary?
10010110011011101 (hexadecimal 12CDD, octal 226335).
What is the square root of 77021?
About 277.5266.
Is 77021 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 77021?
77021 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 7 × 11003, the product of two primes.