A nialpdrome is a nonnegative integer whose standard hexadecimal digits are in nonincreasing order. The first few are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 32, 33, 34, 48, 49, 50, ... (OEIS A023771), corresponding to 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F, 10, 11, 20, 21, 22, 30, 31, 32, ....
The following table summarizes related classes of numbers.
| name | base-16 digit order |
| katadrome | strict descending |
| metadrome | strict ascending |
| nialpdrome | nonincreasing |
| plaindrome | nondecreasing |
