5303 is a prime number. It is a Sophie Germain prime because 2 x 5303 + 1 = 10607 is also a prime. The sum of the digits of 5303 (11) is also a Sophie Germain prime (A118504).
5303 is a balanced prime (the average of the previous prime and the following prime) (A006562). 5297, 5303, and 5309 are three consecutive primes (A053070).
5303 is a prime that is the sum of five consecutive composite numbers (A060330).