N21

N21 or N-21 may refer to:

Buses and trams

• N21 (Long Island bus), New York
• London Buses route N21

Roads

• N21 road (Belgium), a National Road in Belgium
• Route nationale 21, in France
• N21 road (Ireland)
• N21 (Cape Town), in South Africa
• Nebraska Highway 21, in the United States

Other uses

• , a minelayer of the Royal Navy
• Network TwentyOne, an Amway support organization
• Nieuport 21, a French First World War fighter
• Nitrogen-21, an isotope of nitrogen
• Tumbuka language
• N21, a postcode district in the N postcode area