Caitanya-caritāmṛta 20.322
śateka vatsara haya ‘jīvana’ brahmāra pañca-lakṣa cāri-sahasra manvantarāvatāra
[shateka vatsara haya ‘jeevana’ brahmaara pancha-laksha chaari-sahasra manvantaraavataara]
Blended reading (Sanskrit + English inline)
śateka vatsara haya ‘jīvana’ brahmāra pañca-lakṣa cāri-sahasra manvantarāvatāra
“During the hundred years of Brahmā’s life, there are 504,000 manvantara-avatāras.
My note
Source: vedabase.io