Fait mathématique: 5906 is the smallest number which is the sum of 2 rational 4^{th} powers but is not the sum of two integer 4^{th} powers.
Culture générale: 5906 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: March 2nd is the day in 1992 that Armenia, Azerbaijan, Kazakhstan, Kyrgyzstan, Moldova, San Marino, Tajikistan, Turkmenistan and Uzbekistan join the United Nations.