Primecoin is a cryptocurrency based on finding prime numbers. Identifying prime numbers plays a central role in cryptography. Primecoin's unique Proof-of-Work (PoW) consensus mechanism is able to increase transaction speeds and improve energy efficiency.
The network searches for special prime number chains known as Cunningham chains and bi-twin chains, which are of interest in mathematical research.

Telcoin is an Ethereum-based cryptocurrency that will be distributed by mobile network operators. Telcoin (TEL) plans on working with national telecom operators to distribute their currency. They hope that this distribution model will provide greater financial inclusion to un-banked communities, and will encourage cryptocurrency adoption. This is a similar strategy as MPesa, the mobile payment network created by SafariCom, that uses the telecom's provider's existing infrastructure to allow users to easily make payments with their mobile phones. Telecoin sees their platform as a complement to existing mobile money systems that will help drive cryptocurrency adoption.

QChi is an Ethereum-based token with no clear benefits. Their marketing materials do not provide any specific information about their roadmap or what advantages it offers compared to other cryptocurrencies.