2×3×7

2×3×7 denotes the product of the integers 2, 3, and 7. The evaluation of this expression is 42. Its prime factorization is 2×3×7, consisting of three distinct primes, which makes 42 squarefree and a sphenic number.

As a positive integer, 42 has eight divisors: 1, 2, 3, 6, 7, 14, 21, and 42. The sum of all divisors is 96, so the sum of proper divisors is 54; thus 42 is an abundant number (the sum of its proper divisors exceeds the number itself). The Euler totient of 42 is φ(42) = 12. The number is even and composite.

Other arithmetic properties include that 42 is a pronic number, since it can be written as n(n+1) with n = 6 (6×7 = 42). It can also be expressed as a sum of three consecutive integers: 13 + 14 + 15 = 42. Additionally, 42 is a Harshad (Niven) number in base 10, because the sum of its digits 4 + 2 equals 6, and 42 is divisible by 6.

In culture and mathematics, 42 is often noted as the "answer to life, the universe, and everything" from The Hitchhiker's Guide to the Galaxy, contributing to its notoriety outside of pure number theory. In mathematical contexts, 2×3×7 serves as a straightforward example of a product of distinct primes and of a small sphenic, squarefree number.