I got told a secret by a mother of 4 "gifted" children who are past uni stage, all having gone to remarkable unis (she mentioned Oxford and a couple others)
Memory games. Memory, memory, memory. She said her kids aren't gifted LOL they just have good memory, were introduced to reading habits, studying habits and she didn't baby talk them she spoke to them normally.
My dc is 2 and a half and knows 36 elements of the periodic table (we haven't learnt any extra since June as we moved on to second language, will be moving on to the rest of the elements end of the month), vocab is mainly physics and sciences and she got hold of netters anatomy flashcards and rather than play head shoulders bla bla I point at various parts and we name bones, muscles and organs. Make learning fun.
If she asks me a question if I don't know the answer I Google and explain it to her. She doesn't understand, but hell, she sometimes asks a question related to my explanation and she'll remember small bits of that.
Every day activities are also educational, I ask dc to bring me x amount of pegs for example.
Reality is I'm a stay at home parent and give her my 100% which is bloody tiring. I answer all her dumb questions, all her difficult ones. I've had some down time for a month as we were on holiday but boy it's effort.
Now memorising up to 20 is what it is. Understanding the numbers is a different story op 
Same as my child, she has the talk, but does she really understand what her favourite lacrimal bone is 