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.

Quantum Resistant Ledger is developing an enterprise blockchain platform that is designed to be secure against an attack from quantum computers. The Quantum Resistant Ledger (QRL) implements a more secure type of cryptographic signatures call XMSS. The network has a Proof of Stake consensus mechanism.

Divi is a Proof of Stake cryptocurrency with a masternode system designed to encourage network participation. The project is focused on facilitating adoption of cryptocurrencies by creating a system of incentives for both everyday users and those that help run the networks. Divi's masternode system has five layers of participation and awards users for staking their coins. Divi has an innovative lottery block system that randomly pays out lottery prizes in the form of new coins to network users.