7227
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- yes
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 11544
- Proper Divisor Sum (Aliquot Sum)
- 4317
- 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
- 4320
- Möbius Function
- 0
- Radical
- 2409
- Omega Function (Ω)
- 4
- 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
- 132
- Smith Number
- yes
- 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
- no
- Odd
- yes
Appears in sequences
- Let j = | i - i_written_backwards |, k = j + j_written_backwards; then k is in this sequence.at n=35A008920
- a(0) = 1, a(n) = 25*n^2 + 2 for n > 0.at n=17A010015
- a(n) = (d(n)-r(n))/5, where d = A026063 and r is the periodic sequence with fundamental period (1,4,0,0,0).at n=49A026065
- Divisors of 99999999.at n=21A027890
- 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 85.at n=0A031583
- Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 85.at n=0A031763
- Base-10 palindromes that start with 7.at n=14A043042
- Palindromic and divisible by 9.at n=19A045644
- Palindromes with exactly 4 prime factors (counted with multiplicity).at n=35A046330
- Numbers k such that k^2 contains only digits {2,5,9}.at n=10A053928
- T(n,3), array T as in A054134.at n=8A054137
- Palindromes that are the sum of consecutive initial odd composites.at n=3A058850
- a(n) = n^2 + (n^2 with digits reversed).at n=45A061226
- Concatenation of R(n) (A004086) and n, omitting leading 0's.at n=26A071273
- Eighth convolution of A001045(n+1) (generalized (1,2)-Fibonacci), n>=0, with itself.at n=5A073378
- Palindromes in A082939.at n=9A082940
- Palindromes not divisible by any of their digits.at n=41A082947
- Palindromes neither divisible by any of their digits nor by the sum of their digits.at n=39A082948
- Palindromes made of only prime digits.at n=36A084983
- Triangle read by rows in which row n >= 1 gives coefficients in expansion of the polynomial Sum_{k=1..n} (1/n)*binomial(n,k)*binomial(n,k-1)*x^(2k)*(1+x)^(2n-2k) / x^2 in powers of x.at n=46A086873