Any number that you choose can be the next number. It is easy to find a rule based on a polynomial of order 4 such that the first four numbers are as listed in the question followed by the chosen next number. There are also non-polynomial solutions. Short of reading the mind of the person who posed the question, there is no way of determining which of the infinitely many solutions is the "correct" one.
The simplest sequence, based on a polynomial of order 3, is
U(n) = (1793*n^3 - 10749*n^2 + 19702*n - 10740)/6 for n = 1, 2, 3, ... and accordingly, the next number is 7195.
3263442.
A single number, such as 21357, does not define a sequence.
3,263,442
A single number, such as 2481020, cannot define a sequence.
there is a logic progression. 1,2,6,42,1806 (1*1)+1=2 (2*2)+2=6 ... (1806*1806)+1806=3263442 so the sequence would be: 1264218063263442... and so goes on
The next number is 0
It is not possible to identify a sequence when given only one number, as in this questions.
A single number cannot define a sequence.
4
You are multiplying each number in the sequence by -2. Therefore, the next number in the sequence after 32 is -64.
Each following number in the sequence is being divided by 4. Therefore, the next number in the sequence is 3/4 = 0.75.
The next number is the sequence 236175969, 48, 12 is 236175861.