7879
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 31
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 7880
- 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
- 7878
- Möbius Function
- -1
- Radical
- 7879
- 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
- 145
- 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
- 996
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Eleven iterations of Reverse and Add are needed to reach a palindrome.at n=17A015992
- Primes formed by concatenating n with n+1.at n=10A030458
- Pair up the numbers.at n=39A030656
- 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 87.at n=28A031585
- Number of partitions of n such that cn(0,5) = cn(1,5) <= cn(2,5) = cn(4,5) < cn(3,5).at n=67A036863
- Integers n such that A047988(n)=3.at n=38A047986
- Primes whose decimal expansion is a concatenation of two or more consecutive increasing numbers (no leading zeros allowed).at n=11A052087
- Fifth term of strong prime quintets: p(m-3)-p(m-4) > p(m-2)-p(m-3) > p(m-1)-p(m-2) > p(m)-p(m-1).at n=21A054812
- a(n) is the least k > 0 such that sigma(k!) >= n*k!.at n=16A061556
- Numbers which need eleven 'Reverse and Add' steps to reach a palindrome.at n=16A065216
- a(2n) = concatenation of 4n+1 and 4n+2, a(2n+1) = concatenation of the two most nearly equal numbers whose product is a(2n).at n=31A068517
- a(n) is the n-th prime == 1 (mod n).at n=38A077317
- Primes in which odd positioned digits are composite and even positioned digits are primes. The least significant digit is the taken to be the first digit.at n=25A083821
- 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=43A088786
- Smallest number m such that m#/phi(m#) >= n, where m# indicates the primorial (A034386) of m and phi is Euler's totient function.at n=15A091440
- Number of partitions of the n-th decimal palindrome into distinct decimal palindromes.at n=37A091585
- Prime(p)-4 for primes p such that prime(p) - 4 is prime.at n=23A094069
- a(n) = (L(n-2)+2*3^n)/5.at n=9A099159
- Smallest prime equal to the sum of n distinct squares.at n=26A100559
- Upper bound of twin prime pairs whose digital reverse is prime.at n=34A101782