10021
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 4
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 10944
- Proper Divisor Sum (Aliquot Sum)
- 923
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 9100
- Möbius Function
- 1
- Radical
- 10021
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 91
- 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
- Pseudoprimes to base 19.at n=42A020147
- Pseudoprimes to base 48.at n=44A020176
- Strong pseudoprimes to base 48.at n=15A020274
- (d(n)-r(n))/5, where d = A026046 and r is the periodic sequence with fundamental period (1,0,4,0,0).at n=49A026048
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 86 ones.at n=5A031854
- Composite numbers whose prime factors contain no digits other than 1 and 9.at n=11A036309
- Positive numbers having the same set of digits in base 3 and base 10.at n=34A037422
- Lexicographically earliest strictly increasing base 4 autovarious sequence: a(n) = number of distinct a(k) mod 4^n (written in base 4).at n=13A038113
- a(n) * a(n)_reversed is a palindrome (and a(n) is not palindromic).at n=31A048344
- Numbers whose sum of digits is 4.at n=37A052218
- n is odd and sum of digits of n equals the numbers of divisors of n.at n=42A057532
- a(1) = 1; a(n+1) = a(n) + product of nonzero digits of a(n) when written in base 3. Display sequence in base 3.at n=38A063112
- Reflective numbers: k such that the decimal encoding of the prime factorization of k (A067599) is palindromic.at n=42A066985
- Smallest n-digit squarefree number whose internal as well as external digits form a squarefree number greater than 1; or 0 if no such number exists.at n=4A077379
- Divide n-th row of A084024 by n.at n=11A084025
- Numbers n such that numerator(Bernoulli(2*n)/(2*n)) is different from numerator(Bernoulli(2*n)/(2*n*(2*n+1))).at n=38A090177
- a(n) = 88 written in base n.at n=2A095568
- a(n) = 88 written in base 12 - n.at n=9A095569
- Smaller of number pair whose squares are reversals of each other, with no leading zeros allowed.at n=32A106323
- Numbers written in an alternating binary-then-ternary base.at n=41A109827