NumberFieldClassNumber[\[Theta]] gives the class number for the algebraic number field \[DoubleStruckCapitalQ][\[Theta]] generated by \[Theta].
NumberFieldDiscriminant[a] gives the discriminant of the field \[DoubleStruckCapitalQ][a] generated by the algebraic number a.
NumberFieldFundamentalUnits[a] gives a list of fundamental units for the field \[DoubleStruckCapitalQ][a] generated by the algebraic number a.
NumberFieldIntegralBasis[a] gives an integral basis for the field \[DoubleStruckCapitalQ][a] generated by the algebraic number a.
NumberFieldNormRepresentatives[a, m] gives a list of representatives of classes of algebraic integers of norm \[PlusMinus]m in the field \[DoubleStruckCapitalQ][a] generated ...
NumberFieldRegulator[a] gives the regulator of the field \[DoubleStruckCapitalQ][a] generated by the algebraic number a.
NumberFieldRootsOfUnity[a] gives the roots of unity for the field \[DoubleStruckCapitalQ][a] generated by the algebraic number a.
NumberFieldSignature[a] gives the signature of the field \[DoubleStruckCapitalQ][a] generated by the algebraic number a.
NumberFormat is an option for NumberForm and related functions that specifies how the mantissa, base, and exponent should be assembled into a final print form.
NumberForm[expr, n] prints with approximate real numbers in expr given to n-digit precision.