If your favorite number is 712, mathematician Andrew Granville will quickly compute that 712 is 2 times 356, 4 times 178, 8 times 89, or 2 times 2 times 2 times 89. “Every number has a unique way of being written down as a product of primes,” Granville says. “When we study an object in chemistry, we go to atoms; in biology, we go to DNA. For number theorists, it is prime numbers.”
Granville says prime numbers are an example of a deep mathematical idea with the potential to transform other realms of research. But he cautions that an overemphasis on practicality can be dangerous.