1201

This number is a prime.

Apollo 11 received a 1201 computer alarm while descending to the Moon. [McCranie]

The emirp year that starts the first emirp century. Note that deleting the prime digit 2 forms the prime year (101) that starts the first prime century. [Beedassy]

The smallest invertible prime on a calculator display that forms with its reversal a strobogrammatic palindromic prime of form "primemirp": 1201021. The next such prime is 102181 and which forms the strobogrammatic "primemirp" 10218181201. [Beedassy]

1201^2 = 601+602+603...+1799+1800+1801. With 1201, 601, and 1801 each being prime. [Meller]

The smallest half-quartan emirp, i.e., 1201 = (1^4+7^4)/2. [Loungrides]

The first of 9 consecutive emirps. [Goins]

1201 can be written as the sum of consecutive squares (24^2 + 25^2). [Francois]

The smallest prime p, (emirp), such that (p+1)/2, (p+2)/3 and (p+4)/5 are all primes, i.e. 601, 401, 241. Note that a concatenation of these primes, i.e., 601241401, is also prime. [Loungrides]

The smallest Pythagorean prime that forms with its reversal a Pythagorean palindromic prime of form "primemirp": 1201021. [A Pythagorean prime is expressible as a sum of two squares, and its last two digits are 1 (mod 4).] [Beedassy]

The smallest 4-digit prime whose equal partition forms positive primes when added or subtracted, i.e., 12+01 = 13 and 12-01 = 11. [Worrom]