2551
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 2552
- Proper Divisor Sum (Aliquot Sum)
- 1
- 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
- 2550
- Möbius Function
- -1
- Radical
- 2551
- Omega Function (Ω)
- 1
- Little Omega Function (ω)
- 1
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
- 84
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- yes
- Composite Number
- no
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- yes
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 374
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Primes with 6 as smallest primitive root.at n=22A001125
- Central polygonal numbers: a(n) = n^2 - n + 1.at n=51A002061
- Primes of form k^2 + k + 1.at n=17A002383
- A generalized partition function.at n=16A002598
- Sequence A006075 gives minimal number of knights needed to cover an n X n board. This sequence gives number of inequivalent solutions using A006075(n) knights.at n=17A006076
- Coordination sequence T1 for Zeolite Code BRE.at n=33A008058
- Coordination sequence T10 for Zeolite Code MFI.at n=32A008162
- Coordination sequence T1 for Zeolite Code NAT.at n=34A008203
- a(n) = floor( n*(n-1)*(n-2)/27 ).at n=42A011909
- a(n) = Sum_{k=0..n} ceiling(k^3/n).at n=20A014813
- Smallest prime whose digit product is n, if possible; otherwise 0 if n is a prime > 7 or 1 if n has a prime factor > 7.at n=50A016112
- Numbers k such that the continued fraction for sqrt(k) has period 76.at n=2A020415
- Let q_k = p*(p+2) be product of k-th pair of twin primes; sequence gives values of p+2 such that (q_k)^2 > q_{k-i}*q_{k+i} for all 1 <= i <= k-1.at n=23A021007
- Number of partitions of n into 9 unordered relatively prime parts.at n=29A023029
- Primes that remain prime through 2 iterations of the function f(x) = 5x + 8.at n=29A023255
- Primes that remain prime through 2 iterations of function f(x) = 9x + 2.at n=37A023265
- Numbers with exactly 7 1's in their ternary expansion.at n=1A023698
- Every prefix prime in base 6 (written in base 6).at n=18A024766
- a(n) = least m such that if r and s in {1/2, 1/4, 1/6, ..., 1/2n} satisfy r < s, then r < k/m < (k+1)/m < s for some integer k.at n=27A024835
- a(n) = position of the n-th n in A026409.at n=46A026412