2129
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 14
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 2130
- 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
- 2128
- Möbius Function
- -1
- Radical
- 2129
- 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
- 125
- 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
- yes
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 320
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Primes p == 3, 9, 11 (mod 20) such that 2p+1 is also prime.at n=33A000355
- Primes p such that the multiplicative order of 2 modulo p is (p-1)/4.at n=15A001134
- Primes of the form 2^a + 3^b.at n=35A004051
- a(n) = n^2 + prime(n).at n=43A004232
- a(n) = ceiling(n*phi^9), where phi is the golden ratio, A001622.at n=28A004964
- Smallest prime > n^2.at n=45A007491
- Primes of form 3*k^2 - 3*k + 23.at n=24A007637
- Primes p == 1 (mod 8), p = a^2 + 64*b^2 such that y^2 = x^3 + p*x has rank 2.at n=29A007766
- Coordination sequence T4 for Zeolite Code AFR.at n=35A008022
- Coordination sequence T1 for Zeolite Code EPI.at n=29A008090
- Primes p == 1 mod 8 such that 2 and -2 are both 4th powers (one implies other) mod p.at n=36A014754
- Coordination sequence T5 for Zeolite Code TER.at n=31A016437
- Numbers k such that the continued fraction for sqrt(k) has period 43.at n=3A020382
- a(n) = [ a(n-1)/a(1) ] + [ a(n-3)/a(3) ] + [ a(n-5)/a(5) ] + ..., for n >= 3.at n=32A022872
- Primes that remain prime through 2 iterations of function f(x) = 8x + 9.at n=20A023264
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = (Lucas numbers), t = (primes).at n=13A025098
- a(n) = self-convolution of row n of array T given by A027023.at n=6A027040
- Number of partitions of n that do not contain 3 as a part.at n=29A027337
- Numerical distance between m-th and (m+n)-th spheres in loxodromic sequence of spheres in which each 5 consecutive spheres are in mutual contact.at n=15A027674
- Primes in which parity of digits alternates.at n=50A030144