148

148 = 2² x 37.

148 has a representation as a sum of two squares: 148 = 2² + 12².

148 is a heptagonal number. It is also a centered heptagonal number.

148 is the number of perfect graphs with six vertices.

148 x (14 + 8) = 14³ + 8³ = 3256.

Three square numbers using the same digits: 148² = 21904; 203² = 41209; and 302² = 91204.

The astronomical object Arp 148 is the spectacular aftermath of an encounter between two galaxies.

Source: Numeropedia

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!

874

874 = 2 x 19 x 23.

874 is a heptagonal number.

874 is the number of positive integer solutions to (1 + 1/a)(1 + 1/b)(1 + 1/c)(1 + 1/d)(1 + 1/e) = 2.

874 = 0! + 1! + 2! + 3! + 4! + 5! + 6!

874² = 763876 = (7 - 6 - 3 + 876)²

USS Duncan (DDR 874) was a U.S. Navy destroyer, launched in 1945.

Source: What's Special About This Number?

81

81 = 3⁴, a perfect fourth power.

81 is the only integer other than 1 that is the square of the sum of its digits.

81 is a heptagonal number.

81 is a centered octagonal number.

81 = 1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 (the first nine odd numbers).

The chemical element thallium has the atomic number 81.

Source: Number Gossip

469

469 = 7 x 67.

469 is a heptagonal number. 469 is also a centered hexagonal number.

469 is a value of n for which n! - 1 is a prime number.

469 is the sum of three distinct positive cubes: 469 = 7³ + 5³ + 1³.

Inserting a zero between adjacent digits makes 469 a prime number: 40609.

469 Argentina is a main-belt asteroid discovered in 1901.

Source: What's Special About This Number?

34

34 = 2 x 17.

34 is the ninth Fibonacci number.

34 is the smallest number with the property that it and its neighbors have the same number of divisors (four): 33 = 3 x 11; 34 = 2 x 17; 35 = 5 x 7.

The rows and columns of a 4 x 4 magic square always total 34.

34 has a representation as a sum of two squares: 34 = 3² + 5².

34 is the smallest number with four representations as a sum of two primes: 34 = 3 + 31 = 5 + 29 = 11 + 23 = 17 + 17.

34 is 22 in base 16.

34 is a heptagonal number.


34 is the atomic number of the element selenium.

Source: Number Gossip