22
domain: N
Properties
Digital Properties
- Digit Count
- 2
- Digit Sum
- 4
- Digital Root
- 4
- Palindromic Number
- yes
- Repdigit
- yes
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 36
- Proper Divisor Sum (Aliquot Sum)
- 14
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 10
- Möbius Function
- 1
- Radical
- 22
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- no
- Triangular Number
- no
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- yes
- Hexagonal Number
- no
- Lucas Number
- no
- Tetrahedral Number
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 15
- Smith Number
- yes
Classification
- Natural
- yes
- Even
- yes
- Odd
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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
- zweiundzwanzig· ordinal: zweiundzwanzigste
- English
- twenty-two· ordinal: twenty-second
- Spanish
- veintidós· ordinal: 22º
- French
- vingt-deux· ordinal: vingt-deuxième
- Italian
- ventidue· ordinal: 22º
- Latin
- viginti duo· ordinal: 22.
- Portuguese
- vinte e dois· ordinal: 22º
Appears in sequences
- Number of ways of making change for n cents using coins of 1, 2, 5, 10 cents.at n=15A000008
- Expansion of Product_{m >= 1} (1 + x^m); number of partitions of n into distinct parts; number of partitions of n into odd parts.at n=14A000009
- Euler totient function phi(n): count numbers <= n and prime to n.at n=22A000010
- Euler totient function phi(n): count numbers <= n and prime to n.at n=45A000010
- Number of primitive permutation groups of degree n.at n=15A000019
- Number of primitive permutation groups of degree n.at n=35A000019
- Mosaic numbers or multiplicative projection of n: if n = Product (p_j^k_j) then a(n) = Product (p_j * k_j).at n=21A000026
- The positive integers. Also called the natural numbers, the whole numbers or the counting numbers, but these terms are ambiguous.at n=21A000027
- Numbers that are not squares (or, the nonsquares).at n=17A000037
- a(n) is the number of partitions of n (the partition numbers).at n=8A000041
- A Beatty sequence: a(n) = floor(n/(e-2)).at n=15A000062
- Odious numbers: numbers with an odd number of 1's in their binary expansion.at n=11A000069
- Number of positive integers <= 2^n of form x^2 + 4 y^2.at n=6A000072
- a(n) = floor(n^(3/2)).at n=8A000093
- Denumerants: Expansion of 1/((1-x)*(1-x^2)*(1-x^5)).at n=17A000115
- Central polygonal numbers (the Lazy Caterer's sequence): n(n+1)/2 + 1; or, maximal number of pieces formed when slicing a pancake with n cuts.at n=6A000124
- a(n) = 2*(3*n)! / ((2*n+1)!*(n+1)!).at n=4A000139
- Kendall-Mann numbers: the most common number of inversions in a permutation on n letters is floor(n*(n-1)/4); a(n) is the number of permutations with this many inversions.at n=4A000140
- Number of genus 0 rooted maps with 3 faces with n vertices.at n=1A000184
- Lower Wythoff sequence (a Beatty sequence): a(n) = floor(n*phi), where phi = (1+sqrt(5))/2 = A001622.at n=13A000201