... I have an opinion as to this number , though I do not know for certain, for many names have been found in this number when it is expressed in writing. Still we say that perhaps the scription of this same seal will give us the word "I deny."..
Of such kind, in the time of that hater of all good, will be the seal, the tenor of which will be this: "I deny the Maker of heaven and earth, I deny the baptism, I deny my (former) service and attach myself to thee, and I believe in thee."
... truly those who are engrossed in the affairs of life, and with the lust of this world, will be easily brought over to the accuser [Antichrist] then, and sealed by him. - Saint Hippolytus of Rome
"Discourse on the End of the World and on Antichrist"
These men, therefore, ought to learn [what really is the state of the case], and go back to the true number of the name, that they be not reckoned among false prophets. But, knowing the sure number declared by Scripture, that is, six hundred sixty and six, let them await, in the first place, the division of the kingdom into ten; then, in the next place, when these kings are reigning, and beginning to set their affairs in order, and advance their kingdom, [let them learn] to acknowledge that he who shall come claiming the kingdom for himself, and shall terrify those men of whom we have been speaking, having a name containing the aforesaid number, is truly the abomination of desolation. This, too, the apostle affirms: “When they shall say, Peace and safety, then sudden destruction shall come upon them.”47034703 1 Thess. v. 3. And Jeremiah does not merely point out his sudden coming, but he even indicates the tribe from which he shall come, where he says, “We shall hear the voice of his swift horses from Dan; the whole earth shall be moved by the voice of the neighing of his galloping horses: he shall also come and devour the earth, and the fulness thereof, the city also, and they that dwell therein.”47044704 Jer. viii. 16. This, too, is the reason that this tribe is not reckoned in the Apocalypse along with those which are saved.4705
...For if there are many names found possessing this number, it will be asked which among them shall the coming man bear. It is not through a want of names containing the number of that name that I say this, but on account of the fear of God, and zeal for the truth: for the name Evanthas (ΕΥΑΝΘΑΣ) contains the required number, but I make no allegation regarding it. Then also Lateinos (ΛΑΤΕΙΝΟΣ) has the number six hundred and sixty-six; and it is a very probable [solution], this being the name of the last kingdom [of the four seen by Daniel]. For the Latins are they who at present bear rule:47064706 [A very pregnant passage, as has often been noted. But let us imitate the pious reticence with which this section concludes.] I will not, however, make any boast over this [coincidence]. Teitan too, (ΤΕΙΤΑΝ, the first syllable being written with the two Greek vowels ε and ι, among all the names which are found among us, is rather worthy of credit. For it has in itself the predicted number, and is composed of six letters, each syllable containing three letters; and [the word itself] is ancient, and removed from ordinary use; for among our kings we find none bearing this name Titan, nor have any of the idols which are worshipped in public among the Greeks and barbarians this appellation. Among many persons, too, this name is accounted divine, so that even the sun is termed “Titan” by those who do now possess [the rule]. This word, too, contains a certain outward appearance of vengeance, and of one inflicting merited punishment because he (Antichrist) pretends that he vindicates the oppressed.47074707 Massuet here quotes Cicero and Ovid in proof of the sun being termed Titan. The Titans waged war against the gods, to avenge themselves upon Saturn. And besides this, it is an ancient name, one worthy of credit, of royal dignity, and still further, a name belonging to a tyrant. Inasmuch, then, as this name “Titan” has so much to recommend it, there is a strong degree of probability, that from among the many [names suggested], we infer, that perchance he who is to come shall be called “Titan.” We will not, however, incur the risk of pronouncing positively as to the name of Antichrist; for if it were necessary that his name should be distinctly revealed in this present time, it would have been announced by him who beheld the apocalyptic vision. For that was seen no very long time 560 since, but almost in our day, towards the end of Domitian’s reign.
.... But he indicates the number of the name now, that when this man comes we may avoid him, being aware who he is: the name, however, is suppressed, because it is not worthy of being proclaimed by the Holy Spirit. For if it had been declared by Him, he (Antichrist) might perhaps continue for a long period. But now as “he was, and is not, and shall ascend out of the abyss, and goes into perdition,”47084708 Rev. xvii. 8. as one who has no existence; so neither has his name been declared, for the name of that which does not exist is not proclaimed. But when this Antichrist shall have devastated all things in this world, he will reign for three years and six months, and sit in the temple at Jerusalem; and then the Lord will come from heaven in the clouds, in the glory of the Father, sending this man and those who follow him into the lake of fire; but bringing in for the righteous the times of the kingdom, that is, the rest, the hallowed seventh day; and restoring to Abraham the promised inheritance, in which kingdom the Lord declared, that “many coming from the east and from the west should sit down with Abraham, Isaac, and Jacob.”4709
(from Irenaeus - link http://www.ccel.org/ccel/schaff/anf01.ix.vii.xxxi.html
How do we make the proper interpretation of the 666 the number of the name of the beast ? If anyone has other patristic sources our ideas please share.