2107
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 10
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 6
- Divisor Sum
- 2508
- Proper Divisor Sum (Aliquot Sum)
- 401
- 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
- 1764
- Möbius Function
- 0
- Radical
- 301
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 156
- 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
- Number of partitions into non-integral powers.at n=11A000160
- Hex (or centered hexagonal) numbers: 3*n*(n+1)+1 (crystal ball sequence for hexagonal lattice).at n=26A003215
- Divisors of 2^42 - 1.at n=20A003547
- Number of protruded partitions of n with largest part at most 3.at n=12A005404
- Expansion of x*(1+x-x^2)/((1-x)^4*(1+x)).at n=27A005744
- Ruth-Aaron numbers (1): sum of prime divisors of n = sum of prime divisors of n+1.at n=10A006145
- Positive integers n such that 2^n == 2^7 (mod n).at n=50A015927
- Pseudoprimes to base 50.at n=24A020178
- Pseudoprimes to base 79.at n=16A020207
- Pseudoprimes to base 80.at n=20A020208
- Strong pseudoprimes to base 79.at n=7A020305
- Strong pseudoprimes to base 80.at n=7A020306
- Numbers k such that the continued fraction for sqrt(k) has period 24.at n=35A020363
- a(n) = least m such that if r and s in {1/3, 1/6, 1/9,..., 1/3n} satisfy r < s, then r < k/m < s for some integer k.at n=30A024824
- a(1) = 2; a(n+1) = a(n)-th nonprime, where nonprimes begin at 1.at n=23A025003
- a(n) = T(2n,n-1), T given by A026519.at n=6A026526
- a(n) = n*(n + 6).at n=43A028560
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 13 ones.at n=3A031781
- Fractional part of square root of a(n) starts with 9: first term of runs.at n=40A034115
- First gap of n in sequence A038593 (upper terms).at n=34A038662