(define (divisors n)
  (define upper-bound (isqrt n))
  (let loop ([counter 0]
             [divisor 1])
    (cond
     [(fx>? divisor upper-bound)
      (if (fx=? n (fx* upper-bound upper-bound))
             (fx- counter 1)
             counter)]
     [(fxzero? (fxremainder n divisor)) (loop (fx+ counter 2) (fx+ divisor 1))]
     [else (loop counter (fx+ divisor 1))])))

(define (divides-times n divisor times)
  (let loop ([n n] [divisor divisor] [times times])
    (let ([i (/ n divisor)])
      (cond
       [(integer? i) (divides-times i divisor (+ times 1))]
       [else
        times]))))

(define (euler12)
  (let loop ([num 1]
             [sum 1])
    (cond
     [(fx>? (divisors sum) 500) sum]
     [else (loop (fx+ num 1) (fx+ num sum 1))])))