Yes, with Physics 74, Chemistry 81, Mathematics 51, and a VITEEE rank of 21,431, you are eligible for admission at VIT Vellore. You may get core branches like ECE or Mechanical in later rounds, but CSE may be difficult.

Based on your VITEEE rank of 21,431 and the marks you mentioned for Physics (74), Chemistry (81), and Mathematics (51), it seems you might not meet the typical eligibility for admission to the core branches of VIT Vellore (like Computer Science, Electronics, etc.) due to the rank being relatively higher.

However, VIT also offers other branches, and the eligibility can vary for different specializations. Since you are eligible based on the exam (VITEEE), you may still have a chance for admission in some branches, but the chances for more competitive ones like CSE or ECE may be slim.