You've discovered the HHMMSSYYYY format.

I also got this output

strtotime(1458363078) returns FALSE
strtotime(1458373078) returns 34972066717

Why?

https://3v4l.org/TM23M

1458363078 is parsed as 1458=year, 363=day, then invalid characters (PostgreSQL compound format)
1458373078 is parsed as 14=hour, 58=minute, 37=second, year=3078 (time and date formats)

Don't pass Unix timestamps to strtotime.

got it.

Thanks a lot!

As a hint, if you get weird results, use date_parse, and it will tell you how it (tried to) parse the string:

derick@whisky:~ $ php -r 'var_dump(date_parse("1458363078"));'
Command line code:1:
array(12) {
  'year' =>
  int(1458)
  'month' =>
  int(1)
  'day' =>
  int(363)
  'hour' =>
  bool(false)
  'minute' =>
  bool(false)
  'second' =>
  bool(false)
  'fraction' =>
  bool(false)
  'warning_count' =>
  int(1)
  'warnings' =>
  array(1) {
    [11] =>
    string(27) "The parsed date was invalid"
  }
  'error_count' =>
  int(3)
  'errors' =>
  array(3) {
    [7] =>
    string(20) "Unexpected character"
    [8] =>
    string(20) "Unexpected character"
    [9] =>
    string(20) "Unexpected character"
  }
  'is_localtime' =>
  bool(false)
}