8
domain: N
Properties
Digital Properties
- Digit Count
- 1
- Digit Sum
- 8
- Digital Root
- 8
- Palindromic Number
- yes
- Repdigit
- yes
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 0
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 15
- Proper Divisor Sum (Aliquot Sum)
- 7
- 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
- 4
- Möbius Function
- 0
- Radical
- 2
- Omega Function (Ω)
- 3
- Little Omega Function (ω)
- 1
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- yes
- Triangular Number
- no
- Perfect Square
- no
- Perfect Cube
- yes
- 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
- yes
- Narcissistic Number
- yes
- Collatz Steps
- 3
- Smith Number
- no
Classification
- Natural
- yes
- Even
- yes
- Odd
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- yes
- Achilles Number
- no
- Perfect Power
- yes
- Smooth Number
- yes
- Carmichael Number
- no
Names
- German
- acht· ordinal: achte
- English
- eight· ordinal: eighth
- Spanish
- ocho· ordinal: octavo
- French
- huit· ordinal: huitième
- Italian
- otto· ordinal: ottavo
- Latin
- octo· ordinal: octavus
- Portuguese
- oito· ordinal: oitavo
Appears in sequences
- Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.at n=40A000003
- Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.at n=55A000003
- Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.at n=61A000003
- Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.at n=64A000003
- Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.at n=65A000003
- Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.at n=67A000003
- Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.at n=68A000003
- Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.at n=76A000003
- Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.at n=79A000003
- Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.at n=83A000003
- Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.at n=89A000003
- Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.at n=93A000003
- Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.at n=94A000003
- Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.at n=95A000003
- Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.at n=97A000003
- d(n) (also called tau(n) or sigma_0(n)), the number of divisors of n.at n=23A000005
- d(n) (also called tau(n) or sigma_0(n)), the number of divisors of n.at n=29A000005
- d(n) (also called tau(n) or sigma_0(n)), the number of divisors of n.at n=39A000005
- d(n) (also called tau(n) or sigma_0(n)), the number of divisors of n.at n=41A000005
- d(n) (also called tau(n) or sigma_0(n)), the number of divisors of n.at n=53A000005