870
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 2160
- Proper Divisor Sum (Aliquot Sum)
- 1290
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 224
- Möbius Function
- 1
- Radical
- 870
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 4
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
- yes
Recreational
- Happy Number
- no
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 28
- Smith Number
- 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
Classification
- Even
- yes
- Odd
- no
Names
- German
- achthundertsiebzig· ordinal: achthundertsiebzigste
- English
- eight hundred seventy· ordinal: eight hundred seventieth
- Spanish
- ochocientos setenta· ordinal: 870º
- French
- huit cent soixante-dix· ordinal: huit cent soixante-dixième
- Italian
- ottocentosettanta· ordinal: 870º
- Latin
- octingenti septuaginta· ordinal: 870.
- Portuguese
- oitocentos e setenta· ordinal: 870º
Appears in sequences
- a(n) = n^2*Product_{p|n} (1 + 1/p).at n=28A000082
- Construct a triangle as in A036262. Sequence is one less than the position of the first number larger than 2 in the n-th row (n-th difference).at n=29A000232
- Number of compositions of n into 3 ordered relatively prime parts.at n=49A000741
- Stirling numbers of the first kind: s(n+2, n).at n=8A000914
- Smallest even number that is an unordered sum of two odd primes in exactly n ways.at n=46A001172
- Expansion of (1+x^3)/((1-x)*(1-x^2)^2*(1-x^3)).at n=29A001973
- Number of two-rowed partitions of length 3.at n=20A001993
- Oblong (or promic, pronic, or heteromecic) numbers: a(n) = n*(n+1).at n=29A002378
- Denominators of Bernoulli numbers B_{2n}.at n=28A002445
- Denominators of Bernoulli numbers B_{2n}.at n=14A002445
- Smallest number of stones in Tchoukaillon (or Mancala, or Kalahari) solitaire that make use of n-th hole.at n=51A002491
- a(n) = 2*n*(2*n-1).at n=15A002939
- Convolution of A002024 with itself.at n=32A004797
- a(n) = n*(n^2 + 1)/2.at n=12A006003
- Maximal length of rook tour on an n X n board.at n=10A006071
- Denominators of Bernoulli numbers B_0, B_1, B_2, B_4, B_6, ...at n=29A006954
- Denominators of Bernoulli numbers B_0, B_1, B_2, B_4, B_6, ...at n=15A006954
- Consider Leibniz's harmonic triangle (A003506) and look at the non-boundary terms. Sequence gives numbers appearing in denominators, sorted.at n=40A007622
- Expansion of f(f(x)), where f = x + x^2 + x^4 + x^8 + x^16 + ...at n=16A007801
- Number of lattice points inside circle of radius n is 4(a(n)+n)-3.at n=33A007882