What is the limit of the Value Type BigInteger in C#?

Question

As described in MSDN BigInteger is :

An immutable type that represents an arbitrarily large integer whose value in theory has no upper or lower boun

Answer 1

As a confirmation to the answer from Jon Skeet, I looked to the source code of BigInteger. It actually contains two internal properties as follow:

internal int _sign;
internal uint[] _bits;

_bits is used by almost all private/public methods within the class which are used to read/write the actual data.

_sign is used to keep the sign of the BigInteger.

The private methods are extensively using binary operators and calculations. Here is a small list of constants used in the class that might reflect a bit the limits:

private const int knMaskHighBit = -2147483648;
private const uint kuMaskHighBit = 2147483648U;
private const int kcbitUint = 32;
private const int kcbitUlong = 64;
private const int DecimalScaleFactorMask = 16711680;
private const int DecimalSignMask = -2147483648;

PS: I should have commented on J.S. answer, but a comment is too short. To view the source code, either download it or decompile System.Numerics.dll.