Were you able to successfully read the data from Excel into a numeric variable in a SAS data set? That is the first step.
The second step is to use the PUT statement and specify a format that is suitable for your purpose. In the following program, I show how to use the w.d format 30.16, but you might prefer to use 30. if the number is always an integer.
/* Assume that you have read the data into a SAS data set named "Have".
Here, I create the data set with fake data. */
data Have;
input x;
datalines;
1.322E+22
1.23456789E16
;
data Want;
length str $30;
set Have;
str = put(x, 30.16); /* apply a SAS format to convert the number to a string */
run;
proc print; run;
For more information, see "Convert numeric values to character."