smc

$2^{1999}\cdot 5^{2001}=2^{1999}\cdot 5^{1999}\cdot 5^2=25\cdot 10^{1999}$, a number with the digits "25" followed by 1999 zeros. The sum of the digits in the decimal form would be $2+5=7$, thus making the answer $\boxed{7}$.