You can say 百七十ちょい (very casual), 百七十ちょっと (casual), 百七十あまり and 百七十強(きょう) (formal). You can also say 百七十幾つ(ひゃくななじゅういくつ) and 百七十幾ら(ひゃくななじゅういくら), but you cannot use a counter (e.g., 通) with them. 百七十数通(ひゃくななじゅうすうつう) is also acceptable, but it's less common than the others presumably because 170 is already specific enough. 百数十通 is common (roughly between 110 and ...


Off the top of my head, 約【やく】170 大雑把【おおざっぱ】に170くらい 170あまり (implies slightly more than 170) 170弱【じゃく】 (implies slightly less than 170) アバウト170 (just kidding)

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