300 (number) and strictly non-palindromic number. 361 = 19, centered triangular number, centered octagonal number, centered decagonal number, member of the Mian–Chowla sequence; also the number of positions on a standard 19 x 19 Go board. The Bahá'í calendar is based on 19 months of 19 days each. 362 = 2 × 181, Mertens function returns 0, nontotient, noncototient. 363 = 3 × 11, sum of nine consecutive primes (23 + 29 + 31 + 37 + 41 + 43 + 47 + 53 + 59), Mertens function returns 0, perfect totient number. 364 = 2 × 7 × 13, tetrahedral number,
19 (number) 19 (number) 19 (nineteen) is the natural number following 18 and preceding 20. It is a prime number. In English speech, the numbers 19 and 90 are sometimes confused, as they sound very similar. 19 is the 8th prime number. 19 is the seventh Mersenne prime exponent. 19 is the maximum number of fourth powers needed to sum up to any natural number. It is the fourth value of g(k). 19 is the lowest prime centered triangular number, a centered hexagonal number and a Heegner number. The only non-trivial normal magic hexagon contains 19 hexagons (the other being 1). In