unique prime
prime 𝑝 such that there is no other prime 𝑞 such that the period length of the decimal expansion of 1⁄𝑝 equals that of 1⁄𝑞
en-GB/juːˈniːk ˈpɹaɪm/
en-US/juˈnik ˈpɹaɪm/
prime 𝑝 such that there is no other prime 𝑞 such that the period length of the decimal expansion of 1⁄𝑝 equals that of 1⁄𝑞