int oneDays = 60 * 60 * 24;
int oneHours = 60 * 60;
int oneMins = 60;

int day = 987652 / oneDays;
int hour = 987652 % oneDays / oneHours;
int min = 987652 % oneHours / oneMins;
int s = 987652 % oneMins;
Console.WriteLine(day + "天" + hour + "小时" + min + "分" + s + "秒");