2151
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 9
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 6
- Divisor Sum
- 3120
- Proper Divisor Sum (Aliquot Sum)
- 969
- 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
- 1428
- Möbius Function
- 0
- Radical
- 717
- Omega Function (Ω)
- 3
- 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
- yes
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 107
- 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
- no
- Odd
- yes
Appears in sequences
- Expansion of a cusp form of weight 8 for Gamma_1(6).at n=8A006354
- Coordination sequence T2 for Zeolite Code LAU.at n=33A008125
- If a, b in sequence, so is ab+5.at n=32A009304
- Powers of fifth root of 11 rounded up.at n=16A018146
- Numbers k such that the continued fraction for sqrt(k) has period 32.at n=30A020371
- a(n) = a(n-1) + a(n-2) + 1, with a(0) = 1 and a(1) = 7.at n=13A022321
- Ordered sequence of distinct terms of the form floor(x^i * floor(x^j)), i,j >= 0, where x = sqrt(3).at n=32A022769
- Numbers k such that Fibonacci(k) == 34 (mod k).at n=21A023180
- Convolution of the lower and upper Wythoff sequences (A000201 and A001950).at n=13A023664
- Every prefix prime in base 6 (written in base 6).at n=15A024766
- Divisors of 9999999.at n=5A027891
- Numbers k such that k divides the (right) concatenation of all numbers <= k written in base 22 (most significant digit on right).at n=24A029515
- Integer part of decimal 'base-2 looking' numbers divided by their actual base-2 values (denominator of a(n) is n, numerator is n written in binary but read in decimal).at n=46A032532
- Numbers in which all pairs of consecutive base-8 digits differ by 3.at n=37A033079
- a(1) = 2; a(n) is smallest number >= a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.at n=26A033679
- Multiplicity of highest weight (or singular) vectors associated with character chi_21 of Monster module.at n=35A034409
- Zeckendorf expansion of n: repeatedly subtract the largest Fibonacci number you can until nothing remains. Big-endian concatenation of decimals.at n=27A035514
- Number of partitions in parts not of the form 9k, 9k+1 or 9k-1. Also number of partitions with no part of size 1 and differences between parts at distance 3 are greater than 1.at n=38A035940
- a(n) = (s(n)+1)/7, where s(n) = n-th base 7 palindrome that starts with 6.at n=29A043064
- Numbers k such that string 4,7 occurs in the base 8 representation of k but not of k-1.at n=37A044226