7489
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 28
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 7490
- 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
- 7488
- Möbius Function
- -1
- Radical
- 7489
- 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
- 88
- 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
- 949
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Primes of the form m^2 + 3m + 9, where m can be positive or negative.at n=26A005471
- n written in fractional base 10/7.at n=49A024662
- 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 5.at n=37A031418
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 58 ones.at n=6A031826
- Numbers whose base-5 representation contains exactly two 2's and three 4's.at n=26A045288
- 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=29A048270
- Primes whose sum of digits is the perfect number 28.at n=11A048517
- Primes for which only three iterations of 'Prime plus its digit sum equals a prime' are possible.at n=3A048525
- Primes p such that p and p^2 have same digit sum.at n=16A058370
- a(1) = 2; a(n) is the smallest prime > a(n-1) such that a(n) + a(n-1) is a square.at n=12A062064
- Numbers k such that 59^k - 58^k is prime.at n=3A062625
- Primes p such that x^8 = 2 has a solution mod p, but x^(8^2) = 2 has no solution mod p.at n=17A070184
- a(n) = prime(n*(n+1)/2+3).at n=43A078724
- Primes p such that (3*p)^2 + p^2 + 3^2 and (3*p)^2 - p^2 - 3^2 are both prime.at n=19A079796
- G.f. = continued fraction: A(x)=1/(1-x/(1-2*x^2/(1-3*x^3/(1-4*x^4/(...))))).at n=13A088357
- Numbers n which are prime and which when each digit is incremented by 2 with carries ignored yields another prime p with the same property.at n=39A088786
- Largest prime factor of A096421(n).at n=33A097365
- A variation on Flavius's sieve (A000960): Start with the primes; at the k-th sieving step, remove every (k+1)-st term of the sequence remaining after the (k-1)-st sieving step; iterate.at n=34A099207
- Primes of the form 128n+65.at n=16A105129
- Values of c in a^2 + b^2 = c^2 where b - a = 31 and gcd(a,b)=1.at n=6A116509