Any person interested in any tract of land sold at the delinquent sale may redeem the tract at any time within one year after the date of sale by paying to the county treasurer for the purchaser a sum equal to the purchase price stated in the certificate of sale with interest thereon at the rate of 12 per cent per annum from the date of sale to the date of the redemption, together with the amount remaining due and unpaid of any installment upon any assessment on the land under the provisions of this part, with the penalty prescribed for delinquencies.