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The pudendal nerve is the nerve responsible for receiving sensation from the penis. If your penis went numb, it is most likely because you are compressing your pudendal nerve while riding. A google image search of the pudendal nerve will show you the path it takes through the pelvis.
Some things to consider regarding equipment are choosing a good pair of cycling shorts with ample padding. A saddle of the appropriate shape is equally important. Having the saddle positioned properly is the third consideration (a fit expert can help you with this). I find it best to avoid overly padded or gel-type saddles and choose a firm saddle that is shaped properly for your body.
Another factor to consider is remembering to stand and pedal periodically. When group riding, especially on flat roads where the riding position is more static than during climbs and descents, I make sure to stand and pedal whenever I am rotating to the back of the group. Ten seconds of standing on the pedals is enough to ensure that blood flow is increased to the perineum and compression is decreased.