71
domain: N
Properties
Digital Properties
- Digit Count
- 2
- Digit Sum
- 8
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 72
- Proper Divisor Sum (Aliquot Sum)
- 1
- 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
- 70
- Möbius Function
- -1
- Radical
- 71
- Omega Function (Ω)
- 1
- Little Omega Function (ω)
- 1
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
- 102
- Smith Number
- no
Classification
- Natural
- yes
- Even
- no
- Odd
- yes
Primality
- Prime
- yes
- Composite Number
- no
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- yes
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 20
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Names
- German
- einundsiebzig· ordinal: einundsiebzigste
- English
- seventy-one· ordinal: seventy-first
- Spanish
- setenta y uno· ordinal: 71º
- French
- soixante-onze· ordinal: soixante-onzième
- Italian
- settantuno· ordinal: 71º
- Latin
- septuaginta unus· ordinal: 71.
- Portuguese
- setenta e um· ordinal: 71º
Appears in sequences
- Smallest prime power >= n.at n=67A000015
- Smallest prime power >= n.at n=68A000015
- Smallest prime power >= n.at n=69A000015
- Smallest prime power >= n.at n=70A000015
- Mosaic numbers or multiplicative projection of n: if n = Product (p_j^k_j) then a(n) = Product (p_j * k_j).at n=70A000026
- The positive integers. Also called the natural numbers, the whole numbers or the counting numbers, but these terms are ambiguous.at n=70A000027
- 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=33A000028
- Numbers that are not squares (or, the nonsquares).at n=62A000037
- 1-digit numbers arranged in alphabetical order, then the 2-digit numbers arranged in alphabetical order, then the 3-digit numbers, etc.at n=61A000052
- Numbers k such that (2k)^4 + 1 is prime.at n=21A000059
- A Beatty sequence: a(n) = floor(n/(e-2)).at n=50A000062
- Positive zeros of Bessel function of order 0 rounded to nearest integer.at n=22A000134
- Lower Wythoff sequence (a Beatty sequence): a(n) = floor(n*phi), where phi = (1+sqrt(5))/2 = A001622.at n=43A000201
- a(8i+j) = 13i + a(j), where 1<=j<=8.at n=43A000202
- Even sequences with period 2n.at n=6A000206
- a(n) is the least number m such that the n-th prime is the least quadratic nonresidue modulo m.at n=3A000229
- a(n) = n*a(n-1) + (n-3)*a(n-2), with a(1) = 0, a(2) = 1.at n=4A000261
- Remove all factors of 2 from n; or largest odd divisor of n; or odd part of n.at n=70A000265
- Number of partitions into non-integral powers.at n=3A000345
- From a fractal set of positive Lebesgue measure, a self-replicating tiling with holes, the 4-reptile following the 2-reptile of Paul Levy.at n=24A000361