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.

Litecoin is a crytptocurrency that was created to serve as the “silver” to bitcoin’s "gold." It is based on the core Bitcoin protocol, but was designed with several key features that provide it with advantages over Bitcoin.
Litecoin has significantly reduced transaction times by limiting the target block processing time to 2.5 minutes. It also has a total coin supply that is 4 times larger, and utilizes a different hashing algorithm called Scrypt, that requires a smaller workload and less computation power than Bitcoin's SHA-256 algorithm. This enables much faster transactions at a much lower cost to users. These features make Litecoin easier to use and to mine. Since its creation, Litecoin has gained a large market cap and widespread adoption among cryptocurrency users in need of a coin for everyday transactions.