A number is called sN if it is divisible not only by the sum of its digits (like Harshad numbers) but also by the sum of any subset of its (nonzero) digits.
For example, the number 68040 is sN because it is divisible by 6, 8, 4, 6+8, 6+4, 4+8 and 6+4+8.
If is sN, then clearly also
is sN.
The primitive
sN numbers are those such that
is not sN.
It is easy to see that there are infinite primitive sN, because
all the numbers of the form are sN, being divisible
by 1, 2, and 1 + 2 = 3.
The first super Niven numbers are 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 20, 24, 30, 36, 40, 48, 50, 60, 70, 80, 90, 100, 102, 110, 120, 140, 150, 200, 204, 210, 220, 240, 280, 300, 306, 330, 360, 400, 408, 420, 440, 480, 500 more terms