52 is a number whose digits have a product of 10.
511112 is one possible answer.
The 2-digit number must be 20, because it is the only 2-digit number whose sum of its two even digits, 2 + 0 = 2, is greater than the product of its two even digits, 2 x 0 = 0. Moreover, 20 is a product of the two consecutive integers 4 and 5.
There is no such number. If the four digits are even, the entire number is even, not odd.
222
24
It is composite, as are all whole numbers whose last digits are even.
98
Answer 18. The two digit numbers less than 50 whose digits add to 9 are 45, 36, 27 and 18. 36 and 18 are even. 36 is the only number whose paired factor with 2 is even (18).
The only two digit numbers whose digits add up to 17 are 89 and 98. Since 98 is an even number, 89 is prime.
18
754 Piece of cake!
The greatest possible number is 888... (repeating).
4,624 = 682