The payment stays the same every month, but what it buys does not: at the start almost all of it is rent on the outstanding balance, and principal only overtakes interest partway through the term — later than the midpoint of the loan.

01k2k3k0100200300400Half the payment — the level where interest and principal cross
Interest portion of this month's paymentPrincipal portion of this month's paymentHalf the monthly payment
Years before principal first exceeds interest19.39
60
Share of this payment going to interest80%
Amount of this payment that reduces the balance$497

Because the early payments barely touch the balance, the debt owed sits above an equal-steps schedule for the entire term, and the month the balance falls to half the original loan arrives after the halfway point in time.

0100k200k300k400k0100200300400Half the original loan still owed
Balance still owed under the loanBalance if it fell in equal monthly steps

Interactive artifact by Delineo