Integer minutes

I'm studying one Sketch and I can't figure out what
Integer minutes are.

Bellow are two parts of the Sketch with Integer minutes
Any suggestions ?

typedef struct {                     // 5 steps in temperature profile
  char *desc;                        // description 16 char max.
  double Kp, Ki, Kd;                 // PID parameters
  double T1, T2, T3, T4, T5;         // T temperature
  unsigned long t1, t2, t3, t4, t5;  // t time [integer minutes]
} profile;

and

// User Edit    "desc"    ,   Kp,  Ki,  Kd, T1,  T2,  T3,  T4,  T5,  t1,  t2,  t3,  t4,  t5 [t in integer minutes]
  profiles[0] = {"Default"  ,  0.1, 0.3, 0.5,  80,   0,   0,   0,   0, 72000, 0,   0,   0,   0};

thank you,

so I can't enter one and a half minute.

regards
novio