I’ve used Thomas Wang’s integer hash functions for years for various purposes. Using techniques invented by Bob Jenkins for general hashing (e.g., hashes of strings), Wang derived several hash specialized for fixed size integer input. His 64-bit version is uint64_t hash(uint64_t key) { key = (~key) + (key << 21); // key = (key << 21) - key - 1; key = key ^ (key >> 24); key = (key + (key << 3)) + (key << 8); // key * 265 key = key ^ (key >> 14); key = (key + (key << 2)) + (key << 4); // key * 21 key = key ^ (key >> 28); key = key + (key << 31); return key; } Key properties include avalanche (changing any input bit changes about half of the output bits) and invertibility.