7216
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 20
- Divisor Sum
- 15624
- Proper Divisor Sum (Aliquot Sum)
- 8408
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 3200
- Möbius Function
- 0
- Radical
- 902
- Omega Function (Ω)
- 6
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 57
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- yes
- Odd
- no
Appears in sequences
- a(n) = [ 2nd elementary symmetric function of {sqrt(k+1)} ], k = 1,2,...,n.at n=29A025219
- a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ... + a(n-1)*a(1) for n >= 5, with a(1) = 1, a(2) = a(3) = 0, a(4) = 1.at n=14A025276
- Expansion of phi(x) / f(-x) in powers of x where phi(), f() are Ramanujan theta functions.at n=25A029552
- Numbers whose set of base-15 digits is {1,2}.at n=26A032935
- Every run of digits of n in base 15 has length 2.at n=29A033013
- Cycle of 2 steps possible for 'concatenate a(n) and nextprime(a(n)) is a prime'.at n=44A034592
- Number of partitions of n such that cn(0,5) = cn(1,5) <= cn(2,5) = cn(3,5) = cn(4,5).at n=73A036871
- Number of partitions of n such that cn(0,5) = cn(1,5) < cn(2,5) = cn(3,5) = cn(4,5).at n=73A036873
- Number of primes between n*100000 and (n+1)*100000.at n=10A038825
- Positive integers with more base-15 runs of even length than odd.at n=30A044841
- Numbers whose base-4 representation contains exactly four 0's and two 3's.at n=17A045083
- Honaker's triangle problem: form a triangle with base of length n, all entries different, all row sums equal; a(n) gives minimal row sum.at n=35A047837
- a(n) = max_{r=1..n-1} ceiling(t(t(n)-t(r-1))/(n-r+1)), where t() = triangular numbers A000217.at n=35A047873
- Dimension of the space of weight n cuspidal newforms for Gamma_1( 89 ).at n=22A063362
- Harshad numbers which terminate in their digital sum.at n=42A070938
- Product of prime(n+1)-1 and prime(n)-1.at n=22A083553
- Sum of first n 8-almost primes.at n=8A086061
- Numbers n with following property: suppose n^2 = d1 d2 d3 ...dk in decimal; then d1! + d2! + ... + dk! is a square.at n=45A089185
- Square array of numbers associated to the recurrences b(k) = b(k-1) + n*b(k-2); array T(n,k), read by descending antidiagonals, for n, k >= 0.at n=41A110112
- Numbers n such that F(2*n - 1) is prime, where F(m) is a Fibonacci number.at n=25A117595