import datetime
ts = 399513600
dt = datetime.datetime.utcfromtimestamp(ts)
print(dt) # 1982-08-30 00:00:00const ts = 399513600;
const date = new Date(ts * 1000);
console.log(date.toISOString());
// 1982-08-30T00:00:00.000Zimport java.time.Instant;
import java.time.ZoneOffset;
long ts = 399513600L;
Instant instant = Instant.ofEpochSecond(ts);
System.out.println(instant);
// 1982-08-30T00:00:00.000Z