7549
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 25
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 7550
- 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
- 7548
- Möbius Function
- -1
- Radical
- 7549
- 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
- 39
- 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
- 958
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Expansion of x/(1 - 9*x - 4*x^2).at n=5A015580
- 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=17A027674
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 60 ones.at n=11A031828
- Lucky numbers with size of gaps equal to 16 (upper terms).at n=23A031899
- Numbers whose base-4 representation contains exactly four 1's and three 3's.at n=12A045132
- Let (p1,p2), (p3,p4) be pairs of twin primes with p1*p2=p3+p4-1; sequence gives values of p2.at n=14A047977
- Primes p such that x^37 = 2 has no solution mod p.at n=25A059223
- Primes not of the form p + k^2, with p prime and k > 0.at n=14A065377
- Trajectory of n under the Reverse and Add! operation carried out in base 4 (presumably) does not reach a palindrome and (presumably) does not join the trajectory of any term m < n.at n=30A075421
- Smallest prime factor of googol + n that exceeds 13, or 1 if googol + n is 13-smooth.at n=10A076848
- Primes p such that A001414(p-1) and A001414(p+1) are both prime, where A001414 = sum of primes dividing n (with repetition).at n=40A086715
- Primes p such that p-3 and p+3 are divisible by a cube.at n=7A089201
- Smallest prime p such that the concatenation 2,3,5,7, ... (primes) ... p is a multiple of prime(n).at n=45A090497
- a(n) = smallest k such that the base 4 Reverse and Add! trajectory of A075421(n) joins the trajectory of k.at n=30A091676
- Primes of the form 23n+5.at n=42A102734
- Numbers k such that 2*10^k + 8*R_k - 5 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=10A102961
- Primes from merging of 4 successive digits in decimal expansion of cos(1).at n=27A104960
- Primes from merging of 4 successive digits in decimal expansion of exp(Pi).at n=6A105009
- a(1) = 393; for n > 1, a(n) = a(n-1) + 1 + sum of distinct prime factors of a(n-1) that are < a(n-1). edit.at n=42A105210
- Primes with digit sum = 25.at n=36A106763