1231
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 7
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 1232
- 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
- 1230
- Möbius Function
- -1
- Radical
- 1231
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 70
- 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
- 202
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- a(n) = ceiling(1000*log_10(n)).at n=16A004227
- Divisible only by primes congruent to 6 mod 7.at n=36A004624
- Primes written in base 4.at n=28A004678
- Primes written in base 5.at n=42A004679
- Primes of the form k^2 + k + 41.at n=34A005846
- Greater of twin primes.at n=41A006512
- Describe previous term from the right (method A - initial term is 1).at n=4A006711
- a(n) = -Sum_{k = 0..n-1} (n+k)!a(k)/(2k)!.at n=8A007682
- Summarize the previous term! (in decreasing order).at n=4A007890
- Coordination sequence T2 for Zeolite Code AFS.at n=27A008024
- Coordination sequence T2 for Zeolite Code AFY.at n=29A008030
- Coordination sequence T1 for Zeolite Code SGT.at n=22A008229
- Coordination sequence T2 for Zeolite Code VFI.at n=27A008246
- 4-dimensional centered tetrahedral numbers.at n=8A008498
- Expansion of (1+x^5)/((1-x)*(1-x^2)*(1-x^3)*(1-x^4)).at n=42A008766
- Coordination sequence for MgNi2, Position Ni3.at n=9A009934
- a(n) = n*(n-1) + (n-2)*(n-3) + ... + 1*0 + 1 for n odd; otherwise, a(n) = n*(n-1) + (n-2)*(n-3) + ... + 2*1.at n=18A014112
- Odd primes such that (3p+1)/2 and 3p+4 are also prime.at n=16A014223
- From table of maximal epacts e(p) and corresponding primes p, for x_0=2, x_{m+1} = (x_m)^2-1; sequence gives p.at n=18A014426
- Numbers k such that the continued fraction for sqrt(k) has period 44.at n=6A020383