70
domain: N
Properties
Digital Properties
- Digit Count
- 2
- Digit Sum
- 7
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 144
- Proper Divisor Sum (Aliquot Sum)
- 74
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- yes
- Untouchable Number
- no
- Primitive Abundant
- yes
Derived Values
- Euler's Totient
- 24
- Möbius Function
- -1
- Radical
- 70
- Omega Function (Ω)
- 3
- Little Omega Function (ω)
- 3
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
- yes
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- yes
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 14
- Smith Number
- no
Classification
- Natural
- yes
- Even
- yes
- Odd
- 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
Names
- German
- siebzig· ordinal: siebzigste
- English
- seventy· ordinal: seventieth
- Spanish
- setenta· ordinal: 70º
- French
- soixante-dix· ordinal: soixante-dixième
- Italian
- settanta· ordinal: 70º
- Latin
- septuaginta· ordinal: 70.
- Portuguese
- setenta· ordinal: 70º
Appears in sequences
- Number of ways of making change for n cents using coins of 1, 2, 5, 10 cents.at n=26A000008
- Mosaic numbers or multiplicative projection of n: if n = Product (p_j^k_j) then a(n) = Product (p_j * k_j).at n=69A000026
- The positive integers. Also called the natural numbers, the whole numbers or the counting numbers, but these terms are ambiguous.at n=69A000027
- 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=32A000028
- Numbers that are not squares (or, the nonsquares).at n=61A000037
- 1-digit numbers arranged in alphabetical order, then the 2-digit numbers arranged in alphabetical order, then the 3-digit numbers, etc.at n=56A000052
- Numbers k such that (2k)^4 + 1 is prime.at n=20A000059
- Smallest number of vertices in trivalent graph with girth (shortest cycle) = n.at n=7A000066
- Odious numbers: numbers with an odd number of 1's in their binary expansion.at n=35A000069
- a(n) = floor(n^(3/2)).at n=17A000093
- Pell numbers: a(0) = 0, a(1) = 1; for n > 1, a(n) = 2*a(n-1) + a(n-2).at n=6A000129
- Number of partitions into non-integral powers.at n=6A000148
- A Beatty sequence: floor(n*(e-1)).at n=40A000210
- 3*n - 2*floor(sqrt(4*n+5)) + 5.at n=29A000277
- Finite automata.at n=1A000282
- a(n) = (n+1)*(n+3)*(n+8)/6.at n=5A000297
- Number of partitions into non-integral powers.at n=4A000298
- Pentagonal numbers: a(n) = n*(3*n-1)/2.at n=7A000326
- Binomial coefficient binomial(n,4) = n*(n-1)*(n-2)*(n-3)/24.at n=8A000332
- 5th power of rooted tree enumerator; number of linear forests of 5 rooted trees.at n=3A000343