Monday, April 13, 2009

413

413 = 7 x 59.

413 is a semiprime (a product of two primes), but (413 - 4)4 + (413 - 1)1 + (413 - 3)3 is prime with prime length, and contains a prime number of prime digits in its decimal expansion.

413 is a number n such that n and its reversal are both semiprimes: 314 = 2 x 157.

Inserting 9 between adjacent digits of 413 makes it a prime: 49193.


Telephone area code 413 covers Springfield, Mass.

Source: Prime Curios!

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