7211
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
- 7212
- 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
- 7210
- Möbius Function
- -1
- Radical
- 7211
- 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
- 119
- 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
- 921
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Crystal ball sequence for diamond.at n=20A007904
- Numbers k such that the continued fraction for sqrt(k) has period 74.at n=18A020413
- Primes that remain prime through 3 iterations of function f(x) = 2x + 9.at n=15A023276
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 83.at n=32A031581
- Shifts left under inverse Euler transform.at n=36A038071
- Primes with first digit 7.at n=38A045713
- Catafusenes (see reference for precise definition).at n=14A045907
- Sequence of 2 Pythagorean triangles, each with a leg and hypotenuse prime. The leg of the second triangle is the hypotenuse of the first.at n=28A048270
- Primes p such that p+2 and p+8 are also primes but p+6 is not.at n=40A049437
- Primes of the form 2*n^2 + 11.at n=32A050265
- Primes p whose period of reciprocal equals (p-1)/7.at n=8A056212
- Primes p such that |p - q| is a square, where q is the reversal of p.at n=25A059798
- Lesser of irregular twin primes.at n=22A060012
- Non-palindromic primes which on subtracting their reversal give perfect squares.at n=8A080177
- Primes arising in A086498: a(n) = (2n)-th partial sum of A086498.at n=28A086499
- Primes whose reversal is a multiple of 23.at n=36A087767
- Smallest prime of the form prime(k) concatenated with prime(k+n).at n=42A089782
- Smallest prime that begins with the digit reversal of prime(n).at n=30A093487
- Let n! = 2^a*3^b*5^c*7^d.... in canonical form, then a(n) = concatenation a,b,c,d,...at n=7A093881
- Greatest prime that differs from prime(n) in decimal representation by exactly one editing operation: deletion, insertion, or substitution.at n=46A097722