How to write vector form of very large number?

I have to deal with very large numbers like 99^99.

I want these numbers in the vector form. For example, for 5^5=3125 , I should be able to write this in the form {3, 1, 2, 5}

Though the method with sprintf works for some smaller number but num2str-'0' gives negative numbers ?

Answer 1

[David Hill]

You could always use java BigInteger if you don't have symbolic toolbox.

import java.math.*
x=BigInteger(99);
x=x.pow(99);
x=char(x)-'0';

Answer 2

[Walter Roberson]

John D'Errico has a Variable Precision Integer contribution in the file exchange.

Or you use symbolic toolbox if you have that.

[Stephen23]

https://www.mathworks.com/matlabcentral/fileexchange/22725-variable-precision-integer-arithmetic