As others have noted, your question is predicated on a misunderstanding.
Look at Help for STDEV and STDEVP to see the formulas that each uses.

STDEV is the square root of the unbiased estimate of the population
variance if your data is a sample of independant observations. STDEVP
is the population standard deviation if your data is a complete
enumeration of the population.

Jerry

mchsr wrote:

How many std deviations is Excel function "STDEVP"