The total number of longitudes is 360.
Longitudes are imaginary lines drawn from the north pole to the south pole. We have a 0 degree longitude which is the prime meridian.
Prime meridian divides the earth into eastern and western hemispheres. We have 180 degrees east longitude and 180 degrees west longitude which again overlaps to form the anti-meridian.
Thus totalling the east and west meridians we have 180 + 180 = 360 longitudes.