Contradiction with 1 Chronicles 21:1
Contradicts as it discusses a separate census conducted by Satan rather than God as in Numbers 26:63.
1 Chronicles 21:1: And Satan stood up against Israel, and provoked David to number Israel.
Contradiction with Exodus 30:12
Contradicts as it warns of a plague if a census is conducted without a ransom, while Numbers 26:63 describes a census without this condition.
Exodus 30:12: When thou takest the sum of the children of Israel after their number, then shall they give every man a ransom for his soul unto the LORD, when thou numberest them; that there be no plague among them, when [thou] numberest them. [their number: Heb. them that are to be numbered]