CarmichaelLambda[n] gives the Carmichael function \[Lambda](n), defined as the smallest integer m such that k^m \[Congruent] 1 mod n for all k relatively prime to n.

CellChangeTimes is an option to Cell that specifies when changes were made to the cell.

CellDynamicExpression is an option for cells that specifies an expression to be dynamically updated whenever the cell is visible on-screen.

CellTags is an option for Cell that gives a list of tags to associate with a cell.

ChebyshevU[n, x] gives the Chebyshev polynomial of the second kind U_n (x).

ClippingStyle is an option for plotting functions that specifies the style of what should be drawn when curves or surfaces would extend beyond the plot range.

ColorSelectorSettings -> {opt -> val} is a global option that specifies settings for the Color dialog box.

ColumnsEqual is an option for the low-level function GridBox which specifies whether all columns in the grid should be assigned equal width.

CreateIntermediateDirectories is an option for CreateDirectory and related functions that specifies whether to create intermediate directories in a directory path specified.

CreateScheduledTask[expr] creates a task that will repeatedly evaluate expr once per second.CreateScheduledTask[expr, time] creates a task that will repeatedly evaluate expr ...