No zeros occur in this puzzle.
A: D down + M across.
E: the digit sum of K down multiplied with M across.
F: a square number.
G: the greatest common divisor of G across and the reverse of H across equals the reverse of J down.
H: a palindrome.
I: a prime number.
K: a cubic number.
M: a palindrome.
A: the greatest common divisor of A down and H across equals J down.
B: a prime number.
C: both C down and its reverse are prime numbers.
D: M across multiplied with H across.
E: A down multiplied with A down's first digit.
J: a prime number.
K: the reverse of L down.
L: L down < F across.