The number 7777
7777 is a palindrome: it reads 7777 backwards too. Its prime factorisation is 7 × 11 × 101. Divisors (8): 1, 7, 11, 77, 101, 707, 1111, 7777.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 7777: a palindrome: it reads 7777 backwards too.
- 2
7777 is composite. Its prime factorisation is
- 3
The divisors add up to 9792; without 7777 itself that is 2015, so 7777 is deficient (2015 is less than 7777). Euler's totient φ(7777) = 6000 numbers up to 7777 share no factor with it.
- 4
The digits of 7777 add up to 28, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 83 steps to reach 1.
LaTeX source of the formulas on this page
\[ 7777 = 7 \times 11 \times 101 \]
7777 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 9792 |
| Euler totient φ(n) | 6000 |
| Square | 60481729 |
| Cube | 470366406433 |
| Square root | 88.187301 |
| Digit sum / digital root | 28 / 1 |
| Collatz steps to 1 | 83 |
| Scientific notation | 7.777 × |
7777 in other forms
| Form | Value |
|---|---|
| In words | seven thousand seven hundred and seventy-seven |
| Binary (base 2) | 1111001100001 |
| Octal (base 8) | 17141 |
| Hexadecimal (base 16) | 1E61 |
| Base 3 | 101200001 |
| As time | 7777 seconds = 2 h 9 min 37 s |
Is 7777 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 | Yes (7777 ÷ 7 = 1111) | 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 1) | 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 | Yes (7777 ÷ 11 = 707) | 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 7777 a prime number?
No. 7777 = 7 × 11 × 101, so it is divisible by 7.
What are the factors of 7777?
1, 7, 11, 77, 101, 707, 1111, 7777.
What is 7777 in binary?
1111001100001 (hexadecimal 1E61, octal 17141).
What is the square root of 7777?
About 88.1873.
Is 7777 divisible by 3?
No. Its digits add up to 28, which is not a multiple of 3.
What is special about the number 7777?
7777 is a palindrome: it reads 7777 backwards too.