42
domain: N
Properties
Digital Properties
- Digit Count
- 2
- Digit Sum
- 6
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 96
- Proper Divisor Sum (Aliquot Sum)
- 54
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- yes
Derived Values
- Euler's Totient
- 12
- Möbius Function
- -1
- Radical
- 42
- Omega Function (Ω)
- 3
- Little Omega Function (ω)
- 3
Special
- Factorial
- no
- Catalan Number
- yes
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- no
- Triangular Number
- no
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- no
- Hexagonal Number
- no
- Lucas Number
- no
- Tetrahedral Number
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- yes
Recreational
- Happy Number
- no
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 8
- Smith Number
- no
Classification
- Natural
- yes
- Even
- yes
- Odd
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- no
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Names
- German
- zweiundvierzig· ordinal: zweiundvierzigste
- English
- forty-two· ordinal: forty-second
- Spanish
- cuarenta y dos· ordinal: 42º
- French
- quarante-deux· ordinal: quarante-deuxième
- Italian
- quarantadue· ordinal: 42º
- Latin
- quadraginta duo· ordinal: 42.
- Portuguese
- quarenta e dois· ordinal: 42º
Appears in sequences
- Euler totient function phi(n): count numbers <= n and prime to n.at n=42A000010
- Euler totient function phi(n): count numbers <= n and prime to n.at n=48A000010
- Number of series-reduced trees with n nodes.at n=13A000014
- Mosaic numbers or multiplicative projection of n: if n = Product (p_j^k_j) then a(n) = Product (p_j * k_j).at n=41A000026
- Mosaic numbers or multiplicative projection of n: if n = Product (p_j^k_j) then a(n) = Product (p_j * k_j).at n=55A000026
- Mosaic numbers or multiplicative projection of n: if n = Product (p_j^k_j) then a(n) = Product (p_j * k_j).at n=62A000026
- The positive integers. Also called the natural numbers, the whole numbers or the counting numbers, but these terms are ambiguous.at n=41A000027
- Let k = p_1^e_1 p_2^e_2 p_3^e_3 ... be the prime factorization of n. Sequence gives k such that the sum of the numbers of 1's in the binary expansions of e_1, e_2, e_3, ... is odd.at n=20A000028
- Numbers that are not squares (or, the nonsquares).at n=35A000037
- a(n) is the number of partitions of n (the partition numbers).at n=10A000041
- 1-digit numbers arranged in alphabetical order, then the 2-digit numbers arranged in alphabetical order, then the 3-digit numbers, etc.at n=42A000052
- Local stops on New York City 1 Train (Broadway-7 Avenue Local) subway.at n=5A000053
- Local stops on New York City A line subway.at n=4A000054
- Symmetrical dissections of an n-gon.at n=8A000063
- Odious numbers: numbers with an odd number of 1's in their binary expansion.at n=21A000069
- Number of positive integers <= 2^n of form 2*x^2 + 3*y^2.at n=7A000075
- Number of positive integers <= 2^n of form x^2 + 6 y^2.at n=7A000077
- Number of transformation groups of order n.at n=25A000113
- Number of transformation groups of order n.at n=40A000113
- Number of transformation groups of order n.at n=51A000113