I get the same with 5.36.0 as I did with 5.26.1.

Oh, I see. You were adding powers of 2 to the original value of 2**64.
I get the same as you when I run the code you provided.

I was incrementing by one: 
D:\>perl -MMath::BigInt -wle "$x = Math::BigInt->new(~0); $x++; while(
+\"$x\" == ~0){$x++}; print $x;"
18446744073709553665

[download]
Of course, this particular perl configuration sees 18446744073709553665 and 18446744073709554600 as the same value, anyway: 
D:\>perl -le "print 'ok' if 18446744073709553665 == 184467440737095546
+00;"
ok

[download]
However, that your 5.26.1 regards 18446744073709554600 and 18446744073709554599 as different values is a bug in 5.26.1. (I see the same bug in my Windows build of 5.26.0.)
I believe that perl should regard those two values as equivalent for all IV and NV configurations. 
D:\>perl -wle "print 'ok' if 18446744073709554600 == 18446744073709554
+599;"
ok

[download]
For me, that fails to output 'ok' on 5.26.0. (If 5.26.0 has been built with -Duselongdouble, then 5.26.0 does get it right and outputs 'ok'.)

Cheers,
Rob

In reply to Re^4: Number too big to fit in integer by syphilis
in thread Number too big to fit in integer by jpl

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