420 (number)

420 (four hundred [and] twenty) is the natural number following 419 and preceding 421.

← 419 420 421 →
List of numbers — Integers ← 0 100 200 300 400 500 600 700 800 900 →
Cardinal	four hundred twenty
Ordinal	420th (four hundred twentieth)
Factorization	2^2 × 3 × 5 × 7
Greek numeral	ΥΚ´
Roman numeral	CDXX
Binary	1101001002
Ternary	1201203
Octal	6448
Duodecimal	2B012
Hexadecimal	1A416

In mathematics

420 is:

• the sum of four consecutive primes (101 + 103 + 107 + 109).
• the sum of the first 20 positive even numbers.
• a zero of the Mertens function[1] and is sparsely totient.[2]
• a pronic number.[3]
• the smallest number divisible by the numbers 1 to 7, and as a consequence of that it is a Harshad number in every base from 2 to 10 except base 5.
• a 141-gonal number.
• a Harshad number.

In other fields

• 420 is a code-term that refers to the consumption of cannabis.
• 420 is the country calling code for Czech Republic.

References

1. "Sloane's A028442 : Numbers n such that Mertens' function is zero". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-02.
2. "Sloane's A036913 : Sparsely totient numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-02.
3. "Sloane's A002378 : Oblong (or promic, pronic, or heteromecic) numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-02.