UPSC CDS 2 2020 Math Paper

the smallest odd composite number is 9. And 23P62971335 is exactly divisible by 9. So sum of all the digits of the number is also divisible by 9.
Hence 2+3+P+6+2+9+7+1 +3+3+5=41+P=9k;k∈I
So P should be 4 to 23P62971335 is exactly divisible by 9.