In the prime factorization of 12! + 15! + 18! + 21! + 24!, what is the exponent of 3?
12! + 15! + 18! + 21! + 24!==6.204994990790930078976e+23 = 2^10 * 3^5 * 5^2 * 7 * 11 * 53 * 129169 * 189221423
3^5 ==5 is the exponent of 3.
