5721
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 7632
- Proper Divisor Sum (Aliquot Sum)
- 1911
- 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
- 3812
- Möbius Function
- 1
- Radical
- 5721
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 80
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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
- Triangular numbers written backwards.at n=50A004158
- Convolution of (F(2), F(3), F(4), ...) and A014306.at n=17A023656
- 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 50.at n=24A031548
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 50 ones.at n=9A031818
- Numbers whose set of base-8 digits is {1,3}.at n=40A032915
- Base-4 digits are, in order, the first n terms of the periodic sequence with initial period 1,1,2.at n=6A037529
- Base 8 digits are, in order, the first n terms of the periodic sequence with initial period 1,3.at n=4A037580
- Number of partitions satisfying cn(2,5) <= cn(0,5) + cn(3,5) and cn(2,5) <= cn(0,5) + cn(4,5) and cn(3,5) <= cn(0,5) + cn(1,5) and cn(3,5) <= cn(0,5) + cn(4,5).at n=35A039875
- First spoke of a hexagonal spiral.at n=44A056105
- Coordination sequence T3 for Zeolite Code MTF.at n=45A057306
- Composites for which the row of the prime-composite array (A063173) includes the leftmost element of both a zero-only antidiagonal and a zero-only diagonal(A067681).at n=37A063176
- Number of 3-chromatic (i.e., chromatic number equals 3) simple graphs on n nodes.at n=7A076279
- Sum of odd-indexed primes.at n=35A077131
- Triangle read by rows: T(n,k) is the number of simple graphs on n unlabeled nodes having chromatic number k, 1 <= k <= n.at n=30A084268
- Number of meaningful differential operations of the n-th order on the space R^9.at n=10A090994
- Triangle, read by rows, T(n,k) = A000129(n+1) - Sum_{j=1..k} t(n+1, j), where t(n, k) is defined in the formula section.at n=57A103415
- a(n) is the number of distinct n-th powers of functions {1, 2, 3, 4, 5, 6} -> {1, 2, 3, 4, 5, 6}.at n=4A103950
- Semiprimes n such that 3*n - 2 is a square.at n=38A112393
- Semiprimes in A056105.at n=18A113519
- Numbers that are not the sum of two triangular numbers and a fourth power.at n=33A115160