"To be honest, I didn't expect such a public response. I thought it's a nice film and people will enjoy it. I even thought that IPL is on so it would be a bit difficult, and especially there was a match of Mumbai Indians and Kings XI Punjab.
When distributors and exhibitors called me and said that the halls are houseful, I thought I should personally visit and check it, " he told reporters.
Vivek said he sneaked into a hall of the Gaitey Galaxy in Bandra 10 minutes to the film's intermission.
People watching the film were unaware of his presence until media camerapersons came inside the hall and distracted the audience. His fans started howling and whistling and took him on their shoulders, cheering his performance in the film.
"I didn't expect it to be this crazy and I am really sorry for the media people who kind of got pushed around. But I really enjoyed it. Especially, when people started whistling..., " he told reporters.
Vivek went inside the hall unguarded, without any bouncer or police protection. But before the situation could go beyond control, he escaped from the hall through an emergency exit.
The actor also said he was inundated by messages on social networking site Twitter.
"I am in Twitter and you get instant feedback there. Some of them are so cute -- while watching the film they kept on twitting me... right now you did this... now you did that... it's mind blowing. It really feels nice when you get so much love, " he said.
Vivek, who has done mostly multi-starrer films, said it was producer Kumar Taurani's confidence that helped him do the film as a solo lead.
"Honestly speaking I wasn't very sure that I would be able to carry this film. No other known names... till now I have done mostly multi-starrer films so that the films get safe opening. But it was him (Taurani) who saw his prince in me and asked me to give my 100 percent. This is the biggest opening of my career by far, " he said.
"Prince..." narrates the story of a thief who wakes up one morning to realise that he has lost his memory and his life is at stake. The film also features Nandana Sen, Aruna Shields and Neeru Singh.
Vivek, who runs a school in Vrindavan for underprivileged girls who have been abandoned by their families, said he was planning to make a special screening of "Prince..." for them.
"I want to do a special screening for the children in Project Devi in Vrindavan. There are 1, 200 children there but in Vrindavan there is no 1, 200 seat theatre, so I will have to divide them into two shows. My 1, 200 small angels are very excited to see the film with me, " he said.
Asked if he believes that the blessings of these children have brought him success, he said: "Most definitely. If you do some good work, being true to your heart, the blessings you get for it are incomparable. More important than anything else, that takes you to another level, at least spiritually you are very happy by that."