Bob makes his first $$1,000$

deposit into an IRA earning $7\mathrm{.}5$

$\%$ compounded annually on the day he turns $28$ and his last $$1,000$

deposit on the day he turns $48(21$ equal deposits in all$).$ With no additional deposits, the money in the IRA continues to earn $7\mathrm{.}5$

$\%$ interest compounded annually until Bob retires on his $65$th birthday. How much is the IRA worth when Bob retires at $65?$