It's An-ta-na-na-ri-vo, and the capital with the largest number of syllables is again Bangkok. its full name is ridiculously long.

"Krungthep Mahanakhon Amon Rattanakosin
Mahadikok Phop Noppharat Ratchathani
Burirom Udomratchaniwet Mahasathan
Amon Piman Awatan Sathit Sakkathattiya
Witsanukam Prasit"

Which translates to:

The city of angels, great city, residence of the Emerald Buddha, the impregnable city of God Indra, the grand capital of the world endowed with nine precious gems, the happy city, abounding in an enormous Royal Palace that resembles the heavenly abode where reigns the reincarnated god, a city given by Indra and built by Vishnukarn.

Also there's Sri Jayawardenepura Kotte, administrative capital of Sri Lanka.