Primes / Is 73 prime?

Is 73 a Prime Number?

Yes

73 is prime: for 73, testing every prime up to √73 ≈ 8.5 (namely 2, 3, 5, 7) finds no divisor. 73 sits between primes 71 and 79, 2 below and 6 above. 73 shares no factor with 2-12; 73's divisors start beyond that range. 73 is odd, digit sum 10 for 73, digital root 1 for 73. 73 has 5 primes within 10 of 73.