Are there any numbers that don't look prime but are, in fact, prime? [Other than 2, I suppose.]

11, 13, 17 and 19 used to trip me up. And maybe 67

67 has absolutely no right to be prime. Sitting there looking all innocent.

	▲	bombcar 29 minutes ago \| parent [-]
		Maybe that’s the real secret behind the 6-7 meme going around