7272
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- yes
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 24
- Divisor Sum
- 19890
- Proper Divisor Sum (Aliquot Sum)
- 12618
- 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
- 2400
- Möbius Function
- 0
- Radical
- 606
- 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
- 18
- 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
- Kaprekar numbers: positive numbers n such that n = q+r and n^2 = q*10^m+r, for some m >= 1, q >= 0 and 0 <= r < 10^m, with n != 10^a, a >= 1.at n=14A006886
- Sequence satisfies T^2(a)=a, where T is defined below.at n=51A027596
- Multiplicity of highest weight (or singular) vectors associated with character chi_63 of Monster module.at n=36A034451
- Can express a(n) with the digits of a(n)^2 in order, only adding plus signs.at n=47A038206
- Numerators of continued fraction convergents to sqrt(881).at n=4A042702
- Kaprekar numbers: numbers k such that k = q + r and k^2 = q*10^m + r, for some m >= 1, q >= 0 and 0 <= r < 10^m. Here q and r must both have the same number of digits.at n=7A045913
- Bessel function J_0(n) is a monotonically decreasing positive sequence.at n=19A046960
- Bessel function |J_0(n)| is a monotonically decreasing positive sequence.at n=35A046962
- Numbers whose consecutive digits differ by 5.at n=34A048407
- Complete list of 4-Kaprekar numbers.at n=5A053395
- Another version of the Kaprekar numbers (A006886): n such that n = q+r and n^2 = q*10^m+r, for some m >= 1, q >= 0 and 0 <= r < 10^m, with n != 10^a, a >= 1 and n an m-digit number.at n=12A053816
- a(n) = a(n-1) + a(n-2) + (n+2)*binomial(n+3, 3)/2, with a(0) = 1, a(1) = 7.at n=9A054469
- Low-temperature partition function expansion for Kagome net (Potts model, q=4).at n=13A057405
- 1/n has period 4 in base 10.at n=31A069858
- Number of partitions of n with designated summands.at n=21A077285
- Multiples of 6 with only prime digits (2, 3, 5 and 7).at n=23A077535
- Numbers n with property that n is not a power of 2 and the finite sequence n, f(n), f(f(n)), ...., 1 in the Collatz (or 3x + 1) problem contains exactly one prime. (The earliest "1" is meant.)at n=36A078440
- Triangle T(n,k) read by rows, defined by T(n,k) = (n-k)*T(n-1,k)+Sum(k=1..n, T(n-1,k)); T(1,1) = 1, T(1,k)= 0 if k >1.at n=26A089225
- Least k such that k*Mersenne-prime(n)-1 is prime.at n=26A098555
- Real part of absolute Gaussian perfect numbers, in order of increasing magnitude.at n=38A102531