1291
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 1292
- 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
- 1290
- Möbius Function
- -1
- Radical
- 1291
- 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
- 52
- 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
- 210
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Primes p of the form 3k+1 such that -sqrt(p) < sum_{x=1..p} cos(2*Pi*x^3/p) < sqrt(p).at n=28A000922
- Number of plane partitions of n with at most two rows.at n=15A000990
- Number of solutions to a linear inequality.at n=32A002797
- Greater of twin primes.at n=43A006512
- Coordination sequence T3 for Zeolite Code FER.at n=22A008108
- Coordination sequence T4 for Zeolite Code MEL.at n=23A008153
- Molien series for A_9.at n=25A008632
- Number of partitions of n into at most 9 parts.at n=25A008638
- Coordination sequence for MgNi2, Position Mg1.at n=9A009936
- a(n) = prime(n*(n+1)/2).at n=19A011756
- E.g.f.: exp(sinh(arcsin(x)))=1+x+1/2!*x^2+3/3!*x^3+9/4!*x^4+41/5!*x^5...at n=7A012246
- Values of k at which the period of the continued fraction for sqrt(k) sets a new record.at n=23A013645
- Powers of cube root of 2 rounded up.at n=31A017981
- Numbers k such that the continued fraction for sqrt(k) has period 62.at n=0A020401
- Let q_k = p*(p+2) be product of k-th pair of twin primes; sequence gives values of p+2 such that (q_k)^2 > q_{k-i}*q_{k+i} for all 1 <= i <= k-1.at n=18A021007
- Place where n-th 1 occurs in A023122.at n=45A022784
- Primes p such that 4*p + 7 is also prime.at n=40A023215
- Primes p such that 7*p + 4 is also prime.at n=38A023224
- Numbers k such that k and 8*k + 5 are both prime.at n=44A023230
- Primes p such that 10*p + 1 is also prime.at n=47A023237