0o6077
0o6077 is an octal numeric literal. In base-8 notation, the digits used are 0 through 7, and the prefix 0o indicates that the following digits should be interpreted in octal rather than decimal or hexadecimal. The value 0o6077 corresponds to the decimal number 3135.
To understand the conversion, the octal digits are weighted by powers of eight: 6×8^3 + 0×8^2 + 7×8^1
The prefix 0o is used in several programming languages to denote octal literals, most notably Python 3
As with any numeral system, digits above 7 are invalid in an octal literal; attempting to include