- 709 is a prime number.
- Prime factorization: 709 is prime.
- The exponent of prime number 709 is 1. Adding 1 to that exponent we get (1 + 1) = 2. Therefore 709 has exactly 2 factors.
- Factors of 709: 1, 709
- Factor pairs: 709 = 1 x 709
- 709 has no square factors that allow its square root to be simplified. √709 ≈ 26.62705.

**How do we know that ****709**** is a prime number?** If 709 were not a prime number, then it would be divisible by at least one prime number less than or equal to √709 ≈ 26.6. Since 709 cannot be divided evenly by 2, 3, 5, 7, 11, 13, 17, 19, or 23, we know that 709 is a prime number.

Here is today’s puzzle:

Print the puzzles or type the solution on this excel file: 10 Factors 2015-12-07

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Here’s another way we know that 709 is a prime number: Since 22² + 15² = 709, and 22 and 15 have no common prime factors, 709 will be prime unless it is divisible by a primitive Pythagorean hypotenuse less than or equal to √709 ≈ 26.6. Since 709 is not divisible by 5, 13, or 17, we know that 709 is a prime number.

354 + 355 = 709. That is the only way 709 is the sum of consecutive counting numbers.

Because 22² + 15² = 709, it is the hypotenuse of the primitive Pythagorean triple 259-660-709 which was calculated using 22² – 15², 2(22)(15), 22² + 15².

709 is palindrome **595** in BASE 11; note that** 5**(121) +** 9**(11) + **5**(1) = 709.

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Ricardo has tweeted the solution, too:

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```@findthefactors nice game 🙂 pic.twitter.com/l3c03B9NHL

— riccardo (@ricca9380) December 14, 2015