Śrī Raṅganātha, 'the Lord of Raṅgam', is Śrīman Nārāyaṇa reclining in bhujanga-śayana tirukkōlam upon Ādiśeṣa in the great Divya Deśam of Śrīraṅgam. The immovable principal deity (mūlavar) is called Śrī Raṅganātha and, in intimate sampradāya usage, Periya Perumāḷ. The processional deity (utsavar) is Namperumāḷ. The names therefore designate two distinct temple images within the one divine presence and worship of Śrīraṅgam.
Among the 108 Divya Deśams, Śrīraṅgam is honoured simply as Kōyil—'the Temple'—and has an exceptional place in Śrī Vaiṣṇava liturgy, history, and Ācārya-paramparā. This pre-eminence does not require describing Raṅganātha as the sole primary object of worship for every Śrī Vaiṣṇava, since the same Bhagavān is served in many beloved Divya Deśam and household arcā forms.
Arcāvatāra and Saulabhya
Raṅganātha's reclining form is relished as an extraordinary manifestation of Bhagavān's saulabhya: the transcendent Lord has made Himself visible, approachable, and available for service. Many Āzhvārs performed maṅgalāśāsanam to Śrīraṅgam and poured out their experience of its Lord. Their pāsurams celebrate Raṅganātha's beauty, saving qualities, and accessibility. The broad formula that Nammāzhvār declared Śrīraṅgam 'the ultimate destination of all souls' is not a standard summary of any one identified pāsuram.
Śrīraṅgam and the Ācāryas
Śrīraṅgam was the principal institutional centre of Rāmānuja's service and of generations of later Ācāryas. Rāmānuja's revered tāṉ-āṉa tirumēni is enshrined there, and the temple's Prabandha service, festivals, Ācārya sannidhis, and kainkaryam traditions remain central to the living sampradāya. During processions and festivals, Namperumāḷ receives the public and communal services of devotees; in the sanctum, Periya Perumāḷ remains in His ancient reclining form.