Seventy-one

Seventy-one (71, LXXI) is the natural number following seventy and preceding seventy-two. It is the 20th prime number. The next is seventy-three, with which it comprises a twin prime. It is also a permutable prime with seventeen.

Seventy-one is also:

• The atomic number of lutetium, a lanthanide.
• The designation of USA Interstate 71, which runs from Kentucky to Ohio.
• The registry of the U.S. Navy's nuclear aircraft carrier USS Theodore Roosevelt (CVN-71), named after U.S. President Theodore Roosevelt.

This article is about the number. For the year AD 71, see 71.