2621
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 11
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 2622
- 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
- 2620
- Möbius Function
- -1
- Radical
- 2621
- 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
- 146
- 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
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 381
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- One-half the number of permutations of length n without rising or falling successions.at n=6A001266
- Primes of the form 2*k^2 + 29.at n=32A007641
- Coordination sequence T1 for Zeolite Code LEV.at n=38A008127
- Coordination sequence T5 for Zeolite Code DFO.at n=39A009879
- Coordination sequence for MgNi2, Position Ni3.at n=13A009934
- Triangle read by rows: T(n,k) is one-half the number of permutations of length n with exactly n-k rising or falling successions, for n >= 1, 1 <= k <= n. T(1,1) = 1 by convention.at n=35A010028
- Irregular triangle read by rows: T(n,k) (n >= 1, 0 <= k <= [n/2]) = number of permutations of 1..n with [n/2]-k runs of consecutive pairs up and down (divided by 2).at n=23A010030
- Primes that remain prime through 2 iterations of function f(x) = 7x + 6.at n=33A023259
- Index of 9^n within the sequence of the numbers of the form 2^i*9^j.at n=40A025734
- Sum{T(n-k,k)}, 0<=k<=[ n/2 ], where T is the array in A026386.at n=14A026397
- Palindromic primes in base 15.at n=30A029982
- Smallest nontrivial extension of n-th palindrome which is a prime.at n=34A030675
- Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted then there are a pair of central terms both equal to 9.at n=4A031422
- Least term in period of continued fraction for sqrt(n) is 5.at n=14A031429
- a(n) = prime(9*n - 6).at n=42A031913
- a(n) = prime(10*n-9).at n=38A031920
- Lower prime of a difference of 12 between consecutive primes.at n=25A031930
- "DFK" (bracelet, size, unlabeled) transform of 2,1,1,1...at n=27A032215
- Primes of form x^2+53*y^2.at n=27A033234
- Primes p such that Ramanujan function tau(p) is divisible by 11.at n=34A038542