Rajnikanth finds himself to be an orphan. He travels from his village to Madras. There he meets Janakaraj, who gives him a job. By some magical situation, Rajni discovers himself to be a son of a dead millionaire—through Visu. Visu is the guardian of Rajni's father's trust. If Rajni wants his inheritance, he has to follow certain rules. He can get an inheritance of 3000 crore if he can spend 30 crore in a month. The three conditions are: no contributions to charities, not to own any assets at the end of the month, and, above all, no one else must not know. If Rajni fails to spend the money according to the rules, all the money will go to his father's trust which is managed by V.K.Ramasamy, "Nizhalgal" Ravi, Kitty and Raghuvaran. These four form a team of "villains". They want to spoil Rajni's efforts and get all the money for the trust and then to loot the money. Rambha is Visu's daughter and she is appointed as the accountant for Rajni for 30 days.
The music was Composed by Deva. The song "Nagumo" had two versions, Hariharan version was included in soundtrack only, while another version with vocals of Krishnaraj was included in the film only. Audio was released under the music label "ABCL Music" of Amitabh Bachchan.
After the success of Muthu in 1995, Rajinikanth took a year out dabbling in politics and taking a sabbatical before announcing that his next film would be Arunachalam written by Crazy Mohan. It was announced that the film would be produced to help eight of his struggling film industry colleagues and it was incorrectly earlier reported that the film would be produced under his newly floated Rajini Arts banner. It was indicated that some of the people who the film would go on to cause benefits for included Kalakendra Govindharajan who introduced Rajinikanth in his production Apoorva Raagangal (1975), Kalaignyanam who featured Rajinikanth in the lead role for the first time with his production Bairavi (1978) and brothers Ramji and Babji who produced some of the actor's early hits, Kaali (1980) and Garjanai (1980). Furthermore collections would also be shared between the family of Sathya Studio Padmanabhan, actress Pandari Bai, actor V. K. Ramasamy and producer Madurai Nagaraja. Initial reports had also titled the film as Kuberan and Meshtri, but Arunachalam was eventually retained. The plot of the film was inspired by George Barr McCutcheon's novel Brewster's Millions.
Initially the lead heroine of the film was expected to be either Manisha Koirala, who had appeared in successive blockbusters in Bombay and Indian, or Meena who had featured in Rajinikanth's previous film, Muthu. Simran and Shalini was also linked to the role, before Soundarya and Rambha were signed on as heroines. The initial cast list released to the media also had Jayaram in the cast of the film as well as Vignesh, who was later replaced by Raja.Manorama was also surprisingly added to the cast after causing controversy the previous year by lashing out at Rajinikanth's political motives.
Rajinikanth lost his sentimental Rudraksh bead during the shooting of the film and was shocked and upset to note that his Rudraksh was missing. He ordered a search at the shooting spot at midnight and with the help of the giant lights used for shooting, he later found the divine bead after a while.
Indolink.com gave the film a mixed review citing that "the saving grace of the film is Rajini himself. He has the exceptional ability to convincingly portray the same utopian role of anger and love, innocence and impetuousness...and whats more...he does it with remarkable freshness time and again".
The film was declared a commercial success at the box office, although not as big as Rajinikanth's previous blockbusters Baasha and Muthu (both 1995).Arunachalam went on to win three Tamil Nadu State Film Awards, including an award for Best Film. Super Subbarayan and Gopi Kanth also respectively won awards for Best Stunt Coordinator and Best Art Director. The film was later dubbed and released in Telugu under the same name. Rajini's dance with Rambha was a highlight in this movie.