65
domain: N
Properties
Digital Properties
- Digit Count
- 2
- Digit Sum
- 11
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 84
- Proper Divisor Sum (Aliquot Sum)
- 19
- 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
- 48
- Möbius Function
- 1
- Radical
- 65
- 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
- no
- 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
- 27
- Smith Number
- no
Classification
- Natural
- yes
- Even
- no
- Odd
- yes
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
- fünfundsechzig· ordinal: fünfundsechzigste
- English
- sixty-five· ordinal: sixty-fifth
- Spanish
- sesenta y cinco· ordinal: 65º
- French
- soixante-cinq· ordinal: soixante-cinqième
- Italian
- sessantacinque· ordinal: 65º
- Latin
- sexaginta quinque· ordinal: 65.
- Portuguese
- sessenta e cinco· ordinal: 65º
Appears in sequences
- Number of positive integers <= 2^n of form x^2 + 10 y^2.at n=8A000024
- Mosaic numbers or multiplicative projection of n: if n = Product (p_j^k_j) then a(n) = Product (p_j * k_j).at n=64A000026
- The positive integers. Also called the natural numbers, the whole numbers or the counting numbers, but these terms are ambiguous.at n=64A000027
- Numbers that are not squares (or, the nonsquares).at n=56A000037
- a(n) = 2^n + 1.at n=6A000051
- A Beatty sequence: a(n) = floor(n/(e-2)).at n=46A000062
- Number of trees of diameter 4.at n=12A000094
- a(n) = n*(n+3)/2.at n=10A000096
- Denumerants: Expansion of 1/((1-x)*(1-x^2)*(1-x^5)).at n=32A000115
- Positive zeros of Bessel function of order 0 rounded to nearest integer.at n=20A000134
- A Beatty sequence: floor(n*(e-1)).at n=37A000210
- a(n) = floor(n^2/3).at n=14A000212
- Take sum of squares of digits of previous term; start with 3.at n=3A000218
- Remove all factors of 2 from n; or largest odd divisor of n; or odd part of n.at n=64A000265
- a(n) = a(n-1) + a(n-2)^2 for n >= 2 with a(0) = 0 and a(1) = 1.at n=7A000278
- Number of positive integers <= 2^n of form 2 x^2 + 5 y^2.at n=8A000286
- Pentanacci numbers: a(n) = a(n-1) + a(n-2) + a(n-3) + a(n-4) + a(n-5) with a(0) = a(1) = a(2) = a(3) = a(4) = 1.at n=9A000322
- Numbers m such that Fibonacci(m) ends with m.at n=8A000350
- Topswops (1): start by shuffling n cards labeled 1..n. If top card is m, reverse order of top m cards, then repeat. a(n) is the maximal number of steps before top card is 1.at n=11A000375
- Sums of three squares: numbers of the form x^2 + y^2 + z^2.at n=55A000378