18000 tapasvi (ascetics) specifically tied to Neminath Bhagwan is not a standard, widely cited figure in classic Jain scriptures. Tapasvi means an ascetic or mendicant, and while Neminath’s life is described with renunciation and spiritual practices, there is no canonical, universally accepted number of tapasvis given for his era. Different texts and traditions may mention various counts in different contexts, but 18,000 is not a fixed, universally agreed number.

If you want, you can read about Neminath and his life in reputable Jain summaries:

• Shri Neminath Bhagavan (Neminath) — overview and life stories.
• Neminath Jain Derasar (temple context) — related details.
• Shri Girnarji Teerth (Girnar) — Neminath’s Diksha and Moksha associations at this teerth.

If you have a specific text or source that mentions the 18,000 tapasvi, share it and I can explain its context according to Jain tradition.