Taking to the micro-blogging site, Prime Minister Modi wrote: "Birthday greetings to our remarkable former President and statesman Shri Pranab Mukherjee. He has served India with diligence and determination. He is widely admired across the spectrum for his intellect, wit and razor-sharp memory. Praying for his long life."
Pranab Mukherjee, who was the President of India from 2012 to 2017, was awarded the Bharat Ratna, India's highest civilian award, earlier this year by his successor, President Ram Nath Kovind.
Prime Minister Modi and Pranab Mukherjee shared a great bond in their political as well as personal life.
On the last day of Pranab Mujkherjee's tenure as the President, Modi wrote an emotional letter saying: "Pranab Da, you have always been a father figure and a mentor to me," which was shared the former president on his official Twitter account.
Further, Modi wrote: "He had come to New Delhi, three years ago, as an outsider and the task before me was huge and challenging. In these times, you have always been a father figure and a mentor to me. Your wisdom, guidance and personal warmth have given me greater confidence and strength," adding that Mukherjee's "intellectual prowess" had been of constant help.
"You have been so warm, affectionate and caring to me. Your one phone call asking me 'I hope you are taking care of your health' was enough to fill me with fresh energy, after a long day at meetings or on a campaign tour," he said in the letter dated July 24.
In his political career spanning around five decades, Pranab Mukherjee occupied several ministerial portfolios in the Congress or Congress-led coalition governments at the Centre .
Prime Minister Modi was joined in by a number of other political leaders in greeting Mukherjee.
Rajasthan Chief Minister Ashok Gehlot tweeted: "Wishing former President of India, Sh #PranabMukherjee a very happy birthday. Pranab da has spent his entire life in the service of nation & as a leader and statesman. His advice and guidance has been most valuable. May he have a long, healthy, happy life. @CitiznMukherjee."
Taking to social networking site, Punjab Chief Minister Amarinder Singh said: "Wishing Former President Of India, Shri @CitiznMukherjee on his birthday. I pray for your long and healthy life. Your experience, strength, and leadership is a source of inspiration to many. #HappyBirthdayPranabMukherjee"
Extending the greetings, Union Minister Dharmendra Pradhan also tweeted: "Greetings to former President of India, Shri Pranab Mukherjee @CitiznMukherjee on his birthday. India has benefited immensely from his wisdom and statesmanship. I pray to the almighty for Pranab da's well-being and wish him a long, healthy and happy life ahead."
( With inputs from IANS )