420 (number)

← 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	22 × 3 × 5 × 7
Greek numeral	ΥΚ´
Roman numeral	CDXX, cdxx
Binary	1101001002
Ternary	1201203
Senary	15406
Octal	6448
Duodecimal	2B012
Hexadecimal	1A416

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

In mathematics

420 is:

• the sum of four consecutive primes (${\displaystyle 101+103+107+109}$).
• the sum of the first twenty positive even numbers.
• a zero of the Mertens function ^[1] and is sparsely totient. ^[2]
• a pronic number. ^[3]
• The least common multiple of numbers from 1 through 7; ^[4] as a consequence of that, it is a Harshad number in bases 2 to 10, except in base 5.
• a 141-gonal number.^{[ citation needed ]}
• a balanced number. ^[5]
• largely composite number ^[6]

In other fields

• The international country code for Czech Republic.

References

1. Sloane, N. J. A. (ed.). "SequenceA028442(Numbers n such that Mertens' function is zero)". The On-Line Encyclopedia of Integer Sequences . OEIS Foundation.
2. Sloane, N. J. A. (ed.). "SequenceA036913(Sparsely totient numbers)". The On-Line Encyclopedia of Integer Sequences . OEIS Foundation.
3. Sloane, N. J. A. (ed.). "SequenceA002378(Oblong (or promic, pronic, or heteromecic) numbers)". The On-Line Encyclopedia of Integer Sequences . OEIS Foundation.
4. "A003418 - OEIS". oeis.org. Retrieved 2024-11-20.
5. Sloane, N. J. A. (ed.). "SequenceA020492(Balanced numbers: numbers k such that phi(k) (A000010) divides sigma(k) (A000203))". The On-Line Encyclopedia of Integer Sequences . OEIS Foundation.
6. Sloane, N. J. A. (ed.). "SequenceA067128(Ramanujan's largely composite numbers)". The On-Line Encyclopedia of Integer Sequences . OEIS Foundation.