9001
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 10
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 9002
- Proper Divisor Sum (Aliquot Sum)
- 1
- 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
- 9000
- Möbius Function
- -1
- Radical
- 9001
- Omega Function (Ω)
- 1
- Little Omega Function (ω)
- 1
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
- 140
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- yes
- Composite Number
- no
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- yes
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 1118
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Numbers k such that k^2 and k have same last 3 digits.at n=37A008853
- Pisot sequence E(8,14), a(n)=[ a(n-1)^2/a(n-2)+1/2 ].at n=12A014002
- Smallest prime containing n-th square as substring.at n=30A029948
- Smallest nontrivial extension of n-th square which is a prime.at n=29A030685
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 58 ones.at n=10A031826
- Numbers whose set of base-9 digits is {1,3}.at n=42A032916
- (s(n)+1)/10, where s(n)=n-th base 10 palindrome that starts with 9.at n=22A043088
- Primes with first digit 9.at n=15A045715
- Largest prime substring in n! (0 if none).at n=12A046277
- Consider the Diophantine equation x^3 + y^3 = z^3 + 1 (1 < x < y < z) or 'Fermat near misses'. Arrange solutions by increasing values of z (see A050791). Sequence gives values of x.at n=36A050792
- Start with the prime 11; next prime must exceed previous prime and start with last digit of previous prime.at n=8A054262
- Primes p for which the period of reciprocal = (p-1)/8.at n=18A056213
- Numbers k such that k^2 contains only digits {0,1,8}, not ending with zero.at n=5A058421
- Primes p such that p^11 reversed is also prime.at n=36A059704
- Prime having only {0, 1, 4, 9} as digits.at n=39A061246
- a(1) = 2; a(n+1) = smallest prime > a(n) with leading digit equal to final digit of a(n).at n=8A061448
- Primes p such that the greatest prime divisor of p-1 is 5.at n=31A061599
- Primes of form 100*k + 1.at n=27A062800
- a(n) = (9*n^2 + 13*n + 6)/2.at n=44A064226
- 10000n+1, 10000n+3, 10000n+7, 10000n+9 are all primes.at n=5A064963