7121
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
- 7122
- 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
- 7120
- Möbius Function
- -1
- Radical
- 7121
- 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
- 150
- 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
- yes
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 912
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- From a Goldbach conjecture: records in A185091.at n=43A002092
- Rabbytes: group eight successive Fibonacci numbers in reversed binary and translate to decimal.at n=6A006225
- Primes p == 1 (mod 8), p = a^2 +64*b^2 such that y^2 = x^3 + p*x has rank 0.at n=34A007765
- Numbers k such that the continued fraction for sqrt(k) has period 89.at n=5A020428
- Primes that remain prime through 3 iterations of function f(x) = 6x + 1.at n=8A023287
- Number of 4-ary rooted trees with n nodes and height exactly 6.at n=14A036630
- Primes with first digit 7.at n=29A045713
- Sum of first n palindromic primes A002385.at n=19A046485
- p, p+6 and p+8 are all primes (A046138) but p+2 is not.at n=37A049438
- A Diaconis-Mosteller approximation to the Birthday problem function.at n=33A050255
- Primes p from A031924 such that A052180(primepi(p)) = 17.at n=8A052234
- Number of nonempty subsequences {s(k)} of 1..n such that the difference sequence is palindromic.at n=19A053599
- Start with the prime 11; next prime must exceed previous prime, contain no 0's and start with last digit of previous prime.at n=6A053649
- Primes p such that x^16 = 2 has no solution mod p, but x^8 = 2 has a solution mod p.at n=13A059287
- Primes p such that x^48 = 2 has no solution mod p, but x^24 = 2 has a solution mod p.at n=9A059669
- Numerators of partial sums of 1/A051451.at n=7A064888
- Primes p such that x^8 = 2 has a solution mod p, but x^(8^2) = 2 has no solution mod p.at n=16A070184
- Position of the circles around (0,0) that contain record numbers of lattice points in the list of all circles around (0,0) that pass through lattice points, ordered by increasing radius.at n=9A075880
- Duplicate of A023287.at n=8A086126
- Smallest prime equal to the sum of n distinct pairs of consecutive primes.at n=41A102725