71

71 is the 20th prime number.

The numbers 2, 5, 71, 369119, and 415074643 are the only known numbers that divide the sum of all the primes less than themselves.

71 is a centered heptagonal number: 1, 8, 22, 43, 71, 106, 148, 197, . . .

71 is a Google prime. The nth Google number is the first n-digit prime found in the decimal expansion of e: 2, 71, 271, 4523, 74713, . . . The name stems from a famous job ad created by Google that said: “{first 10-digit prime found in consecutive digits of e}.com.”

Some insinuated that each letter could influence the following one and that the value of MCV in the third line of page 71 was not the one the same series may have in another position on another page, but this vague thesis did not prevail.—Jorge Luis Borges, “The Library of Babel”

Source: Number Gossip; Wikipedia
Image: Wikipedia (Claudio Rocchini)