IHOP corp. has agreed to acquire Applebee’s International Inc. for about $2.1 billion. Glendale-based IHOP will pay $25.50 per share in cash for the Overland Park, Kan. restaurant chain, which, along with other casual dining restaurants, has seen its sales slow lately. IHOP plans to franchise most of Applebee’s 500 company owned and operated stores, a reorganization similar to what IHOP did several years ago. “We look forward to applying the same focus and discipline to Applebee’s that we have employed at IHOP over the last several years,” said IHOP Chairman and CEO Julia Stewart. The deal, subject to customary approvals, is expected to close in the fourth quarter.