842
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 14
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 1266
- Proper Divisor Sum (Aliquot Sum)
- 424
- 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
- 420
- Möbius Function
- 1
- Radical
- 842
- 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
- 41
- Smith Number
- no
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
Classification
- Even
- yes
- Odd
- no
Names
- German
- achthundertzweiundvierzig· ordinal: achthundertzweiundvierzigste
- English
- eight hundred forty-two· ordinal: eight hundred forty-second
- Spanish
- ochocientos cuarenta y dos· ordinal: 842º
- French
- huit cent quarante-deux· ordinal: huit cent quarante-deuxième
- Italian
- ottocentoquarantadue· ordinal: 842º
- Latin
- octingenti quadraginta duo· ordinal: 842.
- Portuguese
- oitocentos e quarenta e dois· ordinal: 842º
Appears in sequences
- Number of series-reduced trees with n nodes.at n=18A000014
- Numbers that are not the sum of 4 tetrahedral numbers.at n=42A000797
- a(n) = sigma_2(n): sum of squares of divisors of n.at n=28A001157
- Numbers k such that phi(k) = phi(k+2).at n=20A001494
- a(n) = a(n-1) + a(n-2) + 1, with a(0) = 0 and a(1) = 2.at n=13A001610
- 2nd differences are periodic.at n=21A002082
- a(n) = Sum_{d|n, d == 1 mod 4} d^2 - Sum_{d|n, d == 3 mod 4} d^2.at n=28A002173
- a(n) = n^2 + 1.at n=29A002522
- a(n) = floor(n*phi^14), where phi is the golden ratio, A001622.at n=1A004929
- a(n) = round(n*phi^7), where phi is the golden ratio, A001622.at n=29A004942
- a(n) = ceiling(n*phi^7), where phi is the golden ratio, A001622.at n=29A004962
- a(n) = F(2n+1) + F(2n-1) - 1.at n=7A005592
- Site percolation series for hexagonal lattice.at n=9A006739
- Numbers k such that phi(k) = phi(sigma(k)).at n=35A006872
- Number of cyclic binary n-bit strings with no alternating substring of length > 2.at n=13A007039
- Number of (marked) cyclic n-bit binary strings containing no runs of length > 2.at n=13A007040
- Number of partitions of n into partition numbers.at n=32A007279
- Dodecahedral surface numbers: a(0)=0, a(1)=1, a(2)=20, thereafter 2*((3*n-7)^2 + 21).at n=9A007589
- Numbers k such that k*18^k + 1 is prime.at n=4A007648
- Numbers k such that k!! - 1 is prime.at n=13A007749