– Peyton Manning isn’t just a great pitcher, he’s also a great pitchman, so you wonder why he hasn’t channeled his inner entrepreneur and capitalized on all that prime real estate he’s carried around with him all week.

That is, his forehead. His brain isn’t just famous. It’s protruding. His forehead is a mobile Times Square billboard, which is fitting, because Manning is a square for our times.

If Tom Brady is George Clooney in cleats, Manning is what you would get if Bill Gates could throw a fluttering forward pass.

When you looked at Brett Favre up close, you noticed the meathook hands and dockworker’s forearms, the jutting, grizzled chin. Brady is glamour incarnate. What you notice about Manning up close is that he hikes his sweats high on his waist like a septuagenarian mall-walker, and that, despite his prototypical height and weight, he exudes the aura of a stats geek.

With a victory Sunday, Manning will gild a résumé that might be the greatest in the history of quarterbacks, if not football at large, and yet he’s more famous for his film study and extemporaneous play calling than his arm.

Teammates say he has a photographic memory, which is something he shares with Super Bowl viewers. Already the owner of the greatest statistical résumé of any quarterback in history, Manning knows that what he does Sunday will become the latest and thus most prominent stamp on his passport.

If he wins, he will become the first quarterback ever to win Super Bowls with two teams. He will have won in his prime with his original franchise, and at 37 following four neck surgeries; with a dome team that beat the Bears in the rain in Miami, and with a high-altitude franchise that will have survived the cold and wind on a February Sunday in New Jersey.

The son of an NFL quarterback (Archie) and brother of another (Eli), Manning studies league history almost as much as he studies game tapes.

Asked if he knew the other two quarterbacks who started for different teams in the Super Bowl, Manning said: “I can name them. Do you want me to help you with the answer? [Kurt] Warner and Craig Morton were the two. I saw Kurt this week. Craig Morton did it with Denver and Dallas. That to me is a special accomplishment in itself.

“I know how hard it’s been for me to transition to a new organization. To try to get comfortable with the new culture you are playing in and surroundings, just to get comfortable, is hard enough. To actually turn it into some production and help your team get back to this game, it’s hard to do. I’m proud what this team has accomplished this year.’’

Beating Seattle’s top-ranked defense in cold weather will be like solving a Rubik’s Cube while wearing mitttens. A quarterback who relies on timing, precision and a less-than-aerodynamic spiral can be affected more than a flamethrower like Favre in nasty conditions, and even Favre became less effective in cold weather as he aged.

According to the Denver Post, Manning is 0-3 when he plays in temperatures below 20 degrees, 2-5 when the temperature is between 20 and 29 and 6-5 when it is between 30 and 39. The temperature on Sunday in New Jersey is expected to hover in the 40s.

Manning didn’t dwell much on the cold or his body of work this week, but he knows that a victory over a great defense in cold weather would apply white-out to the few smudges on his résumé.

“I’ve been asked about my legacy since I was 25,’’ he said. “I’m not even sure you can have a legacy when you’re 25, or even 37. I thought you had to be 70 to have a legacy.

“I’m not 100 percent sure what the word even means. I’m down the homestretch of my career, but I’m still in it. It’s not over yet. It’s still playing out. This has been the second chapter in my career, and it is an exciting chapter.’’

Manning hasn’t clearly answered questions about his retirement plans, but with two more seasons he should pass Favre for most passing yards in NFL history, and perhaps win another Super Bowl.

With a victory on Sunday and another productive season or two, Manning would no longer be in the conversation about the greatest quarterbacks of all time. He would turn himself into the only possible answer.