7861
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 8992
- Proper Divisor Sum (Aliquot Sum)
- 1131
- 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
- 6732
- Möbius Function
- 1
- Radical
- 7861
- 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
- 145
- 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
- Numerators of coefficients of Green function for cubic lattice.at n=4A003284
- Expansion of 1/((1-3x)(1-5x)(1-6x)).at n=4A017269
- Pseudoprimes to base 33.at n=26A020161
- Strong pseudoprimes to base 34.at n=7A020260
- Denominators of continued fraction convergents to sqrt(821).at n=9A042585
- Number of asymmetric (identity) trees with n nodes and 5 leaves.at n=13A055336
- Number of partitions of n with nonnegative rank.at n=34A064174
- Number of ordered triples (a, b, c) with gcd(a, b, c) = 1 and 1 <= {a, b, c} <= n.at n=20A071778
- List of codewords in binary lexicode with Hamming distance 5 written as decimal numbers.at n=31A075931
- Sum of even-indexed primes.at n=40A077126
- Beginning with 1, numbers such that the differences a(k)-a(k-1) are distinct and every concatenation n>1 is prime.at n=42A090504
- Fundamental discriminants of real quadratic number fields with class number 5.at n=35A094614
- a(1) = 3, a(n) = least k such that concatenation of n copies of k with all previous concatenation gives a prime.at n=43A111473
- Numbers n such that p(5n) is prime, where p(n) is the number of partitions of n.at n=22A114166
- Row sums of correlation triangle for floor((n+3)/3).at n=38A115266
- Number of base 11 circular n-digit numbers with adjacent digits differing by 6 or less.at n=4A125399
- Binomial transform of reduced tangent numbers (A002105).at n=9A154603
- The second of a pair of sequences A and B with property that all the differences |a_i - b_j| are distinct - for precise definition see Comments lines in A169677.at n=42A169678
- Matrix inverse of triangle A227342.at n=31A227343
- Irregular triangle read by rows: row n lists the rank sizes of the "electrical" poset EP_n of circular planar graphs with n boundary vertices.at n=51A232967