600

600 = 2³ x 3 x 5².

600 is the product of two consecutive integers, so it is a pronic number: 600 = 24 x 25.

600 and its reverse, 6, are both the averages of twin primes: 599 and 601; 5 and 7.

600 is 211020 in base 3 and 21120 in base 4; it is 4400 in base 5, 2440 in base 6, and 420 in base 12; it is 1515 in base 7.

600 is the value of the postal abbreviation for the District of Columbia, DC, in the United States, interpreted as Roman numerals.

Source: Number Gossip