273

273 = 3 x 7 x 13.

273 is 100010001 in base 2 (binary), 333 in base 9, and 111 in base 16.

The 273rd prime minus the sum of gaps between the first 273 consecutive primes minus 1 equals 273.

273 is the sum of each of two consecutive sums of consecutive numbers: 273 = 36 + 37 + 38 + 39 + 40 + 41 + 42 = 43 + 44 + 45 + 46 + 47 + 48.

The zero on the Celsius temperature is 273 (to the nearest whole number) on the Kelvin temperature scale.

Source: Prime Curios!