I search the number nearest to $5^{5^3} = 5^{125}$, which is product of two $44$-digit primes.
The direct method is : Begin with $N = 5^{125}$. Increase $N$ until the desired number is found. Whenever a small factor is found, the number need not to be factored completely. Do the same with decreasing, beginning with $N$. The two found numbers have the form $N-a$ and $N+b$. Choose the number nearer to $5^{125}$. The method is trivial, but very time-consuming.
Is there a way to find the number faster?
I believe the closest number to $5^{125}$ which is product of two 44-digit primes is $5^{125}-588$:
It was found by testing the numbers $5^{125}\pm 1$, $5^{125}\pm 2$, ...; checking if they have any factor smaller than $10^9$ first and running the general-purpose factorizer on them otherwise.