1818
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 3978
- Proper Divisor Sum (Aliquot Sum)
- 2160
- 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
- 600
- Möbius Function
- 0
- Radical
- 606
- Omega Function (Ω)
- 4
- 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
- no
- Hexagonal Number
- no
- Lucas Number
- no
- Tetrahedral Number
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- yes
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 16
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
Appears in sequences
- Self numbers divisible by sum of their digits (or, self numbers which are also Harshad numbers).at n=41A003219
- Numbers n such that n^32 + 1 is prime.at n=34A006315
- Inverse Moebius transform applied twice to squares.at n=31A007433
- Coordination sequence T1 for Zeolite Code DAC.at n=27A008067
- Coordination sequence T3 for Zeolite Code GOO.at n=29A008113
- Coordination sequence T3 for Zeolite Code MTN.at n=25A008188
- Let j = | i - i_written_backwards |, k = j + j_written_backwards; then k is in this sequence.at n=22A008920
- a(n) = floor(binomial(n,3)/3).at n=33A011849
- a(n) = 4*a(n-1) + n with n > 1, a(1)=1.at n=5A014825
- Doublets: base-10 representation is the juxtaposition of two identical strings.at n=17A020338
- Index of 10^n within the sequence of the numbers of the form 4^i*10^j.at n=46A025742
- a(n) = greatest number in row n of A026098 that is not a positive power of 2.at n=40A026104
- a(n) = sum of the numbers between the two n's in A026354.at n=39A026357
- Numbers k such that k(k+1)(k+2)...(k+9) / (k+(k+1)+(k+2)+...+(k+9)) is an integer.at n=27A032782
- Alternating sum transform (PSumSIGN) of A000975.at n=11A034299
- Positive numbers having the same set of digits in base 5 and base 8.at n=20A037431
- T(n,n-3), array T as in A038792.at n=22A038793
- Numbers having two 8's in base 10.at n=36A043522
- Numbers k such that string 0,5 occurs in the base 7 representation of k but not of k-1.at n=41A044143
- Numbers n such that string 3,2 occurs in the base 8 representation of n but not of n-1.at n=32A044213