437

This number is a composite.

π(437) = 4*3*7. [Kumar]

437 + 6, 66, 666, 6666, 66666 and 666666 is prime. [Petrov]

The smallest tetranacci brilliant number (437 = 19 × 23) defined by the four prime digits (T₀=2, T₁=3, T₂=5, T₃=7) and the recurrence relation: T_n = T_n-1 + T_n-2 + T_n-3 + T_n-4. [Loungrides]

(There is one curio for this number that has not yet been approved by an editor.)