7. A natural number, the sum of its largest divisor and its second largest divisor is 111, this natural number is
7. Solution: Since 111 is an odd number, and odd number $=$ odd number + even number, the greatest divisor and the second greatest divisor of the required number must be one odd and one even. The greatest divisor of a number is the number itself, and if a number has an even divisor, this number must be even, and the second greatest divisor of an even number should be half of this even number. Let this second greatest divisor be $\mathrm{a}$, then the greatest divisor is $2 \mathrm{a}$, $\mathrm{a}+2 \mathrm{a}$ $=111$, solving for $a=37, 2a=74$, so the required number is 74.