189

189 = 3³ x 7.

The product of the four primes in a prime quadruplet (except for 5, 7, 11, 13) always ends in 189. Example: 101 x 103 x 107 x 109 = 121,330,189.

189 is a heptagonal number. It is also a centered cube number.

189 is 10111101 in base 2 (binary). It is 99 in base 20 and 90 in base 21.

189 is a divisor of 55² - 1.

The 189th century will be the first to contain as few as five prime years: 18803, 18839, 18859, 18869, and 18899.

Source: Prime Curios!

855

855 = 3² x 56 x 19.

855 is the sum of all the digits of all two-digit numbers.

855 is a number that cannot be written as a sum of three squares.

855 is a decagonal number. It is also a centered cube number.

855 is the smallest number that is the sum of five consecutive squares and two consecutive cubes: 855 = 11² + 12² + 13² + 14² + 15² = 7³ + 8³.

855 Newcombia is a asteroid discovered in 1916.

Source: Number Gossip