400 (number) third perfect number, a number whose divisors add up to the actual number (1+2+4+8+16+31+62+124+248=496). 497 = 7 × 71, sum of five consecutive primes (89 + 97 + 101 + 103 + 107) 498 = 2 × 3 × 83, sphenic number, untouchable number, admirable number, abundant number A prime number, Chen prime 400 (number) 400 (four hundred) is the natural number following 399 and preceding 401. 400 is the square of 20. 400 is the sum of the powers of 7 from 0 to 3, thus making it a repdigit in base 7 (1111). A circle is divided into
Root Letter Root Letter Root Letter, stylized as √Letter, is a 2016 visual novel adventure video game developed and published by Kadokawa Games for PlayStation 4, PlayStation Vita, Microsoft Windows, Android, and iOS. It is the first entry in the "Kadokawa Game Mystery" brand, and is to be followed by the upcoming "Root Letter 2". The game plays as an adventure visual novel. In the game, the player must figure out what happened to the character of Aya, a girl who mysteriously vanished after receiving a particular letter. The gameplay will be split into two distinct parts; the adventure part, where the