5215
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 7200
- Proper Divisor Sum (Aliquot Sum)
- 1985
- 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
- 3552
- Möbius Function
- -1
- Radical
- 5215
- Omega Function (Ω)
- 3
- Little Omega Function (ω)
- 3
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
- 85
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- no
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Nearest integer to modified Bessel function K_n(5).at n=14A000249
- Coordination sequence T1 for Banalsite.at n=43A008249
- Place where n-th 1 occurs in A023125.at n=37A022787
- a(n) = 1*t(n) + 2*t(n-1) + ... + k*t(n+1-k), where k=floor((n+1)/2) and t = A008578 ({1} U primes).at n=25A023862
- a(n) = 1*prime(n) + 2*prime(n-1) + ... + k*prime(n+1-k), where k=floor((n+1)/2) and prime(n) is the n-th prime.at n=24A023870
- Every suffix prime and no 0 digits in base 6 (written in base 6).at n=40A024781
- a(n) = floor( tan(m*Pi/2) ), where m = 1 - 2^(-n).at n=12A024810
- Numbers n such that n divides the (right) concatenation of all numbers <= n written in base 16 (most significant digit on right).at n=26A029509
- Numbers k such that 207*2^k + 1 is prime.at n=36A032480
- a(n) = n * prime(n).at n=34A033286
- Conjecturally, a power of 2 written in base 3 cannot have this many 2's.at n=35A036463
- Numbers whose base-4 representation contains exactly four 1's and two 3's.at n=25A045131
- Palindromes in factorial base.at n=40A046807
- Number of n X n 0..6 matrices with all row and column sums equal.at n=3A067214
- Number of ways to tile a 4 X n room with 1x2 Tatami mats. At most 3 Tatami mats may meet at a point.at n=47A068923
- Indices of spheres mentioned in A071609.at n=42A076180
- Leading diagonal of A083173.at n=34A083174
- Indices of primes in sequence defined by A(0) = 51, A(n) = 10*A(n-1) + 31 for n > 0.at n=12A101578
- Triangle T(n,k), 0<=k<=n, read by rows defined by: T(n,k) = T(n-1,k-1) + 2*T(n-1,k) + T(n-2,k-2) - T(n-2,k), T(0,0) = 1, T(n,k) = 0 if k < 0 or if n < k.at n=50A102756
- n times n+7 gives the concatenation of two numbers m and m+7.at n=5A116340