This is pretty easy if you understood that we live in a world of base 10 and the principles of division with rest:

    n = 781049;
    Rest@Reverse[Flatten@Last@Reap@FixedPointList[(Sow[Mod[#, 10]]; Quotient[#, 10]) &, n]]
    (* {7, 8, 1, 0, 4, 9} *)

or as J.M. suggested with one call to get the quotient and the remainder


    With[{n = 781049}, Reverse[Reap[NestList[Block[{q, r}, 
     {q, r} = QuotientRemainder[#, 10]; Sow[r]; q] &, n, IntegerLength[n]]][[-1, 1]]]]

If you really prefer shorter methods, than you could go with

    IntegerDigits[n]

or maybe

    ToExpression@StringCases[ToString[n], DigitCharacter]

if you like strings.