57 (fifty-seven) is the natural number following 56 and preceding 58. It is a composite number. 57 is semiprime [1] a Blum integer, [2] and a Leyland number. [3] The split Lie algebra E 7 1 2 has a 57-dimensional Heisenberg algebra as its nilradical, and the smallest possible homogeneous space for E 8 is also 57-dimensional. [4] More @Wikipedia
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