**305**= 5 x 61.

**305**is the smallest odd composite that is the average of two consecutive Fibonacci numbers (233 and 377).

**305**has two representations as a sum of two squares:

**305**= 4

^{2}+ 17

^{2}= 7

^{2}+ 16

^{2}.

**305**is the hypotenuse of two primitive Pythagorean triples:

**305**

^{2}= 136

^{2}+ 273

^{2}= 207

^{2}+ 224

^{2}.

**305**is a divisor of 11

^{4}- 1.

**305**is the fifth hexagonal prism number. A hexagonal prism number has the form (

*n*+ 1)(

*n*

^{2}+ 3

*n*+ 1).

**305**is 614 is base 7 and 461 in base 8.

Source: Prime Curios!