The number 761
761 is the 135th prime number. Its only divisors are 1 and 761.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 761: the 135th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
761 is prime, so its only factors are 1 and 761. It is the 135th prime; the next prime is 769 and the one before is 757.
- 3
The divisors add up to 762; without 761 itself that is 1, so 761 is deficient (1 is less than 761). Euler's totient φ(761) = 760 numbers up to 761 share no factor with it.
- 4
The digits of 761 add up to 14, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 33 steps to reach 1.
761 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 762 |
| Euler totient φ(n) | 760 |
| Square | 579121 |
| Cube | 440711081 |
| Square root | 27.586228 |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 33 |
| Scientific notation | 7.61 × |
761 in other forms
| Form | Value |
|---|---|
| In words | seven hundred and sixty-one |
| Roman numerals | DCCLXI |
| Binary (base 2) | 1011111001 |
| Octal (base 8) | 1371 |
| Hexadecimal (base 16) | 2F9 |
| Base 3 | 1001012 |
| As time | 761 seconds = 12 min 41 s |
Is 761 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 | No (remainder 5) | 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 5) | 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 2) | 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 761 a prime number?
Yes. 761 is divisible only by 1 and itself.
What are the factors of 761?
1, 761.
What is 761 in binary?
1011111001 (hexadecimal 2F9, octal 1371).
What is the square root of 761?
About 27.5862.
What is 761 in Roman numerals?
DCCLXI.
Is 761 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 761?
761 is the 135th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.