"This phone's going to be launching into an install base that's 50 percent bigger than the last big phone, the iPhone 6, launched into. So even if the upgrade rate is way lower, they're going to sell way more phones," Arcuri said. "I think the numbers are still way too low."

Analysts surveyed by FactSet expect the tech giant to sell 82 million iPhone units during this year's holiday quarter, up from 78 million last year. But Wall Street might be lowballing Apple's wide base of existing iPhone users who are itching for an upgrade, Arcuri told CNBC's " Squawk on the Street " on Monday.

People are vastly underestimating how big s next iPhone cycle will be, said Timothy Arcuri, managing director at Cowen and Co.

Last year, Apple reported of lower year-over-year sales, adding up to its first yearly decline since 2001. But a confluence of factors — Apple's return to iPhone sales growth, investments by famed investor and the company's ambitions to double its services revenue — all came together at the right time, said Brian White, global head of technology hardware and software at Drexel Hamilton.

"I think this still remains one of the most underappreciated stocks in the world," White said on "Squawk on the Street." "I think what people are starting to understand is they were negative on Apple for all the wrong reasons."

Shares of Apple have already risen nearly 24 percent over the past three months. During the first quarter, the company added more than $140 billion to its market capitalization, more than the gains of the other 29 Dow components combined.

Source: FactSet

Keeping the Apple ecosystem interesting with additions like original content might help the company sell more phones, the analysts said.

"They have at least one more big phone cycle here. There's a ton of innovation yet to come in the phone," Arcuri said. "You're going to have a foldable phone from Apple probably by 2019 ... I think there's a lot more lengths to go with just the phone. "

To be sure, while Apple is shelling out big time on , it is notoriously secretive about its new products.

"What they are creating here is a vehicle that can capitalize on the world as it becomes a computer," White said. "Whether it's a TV, whether it's a watch, whether it's your home, whether it's a car. ... Today the phone is the biggest piece of it, but I think it's going to give people kind of the walkway into these other areas over time."

Disclosure: Apple is an investment banking client of Drexel Hamilton.