7924
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
- 2
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 15904
- Proper Divisor Sum (Aliquot Sum)
- 7980
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- yes
Derived Values
- Euler's Totient
- 3384
- Möbius Function
- 0
- Radical
- 3962
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 3
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
- 101
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- yes
- Odd
- no
Appears in sequences
- Let F(x) = 1 + x + 4x^2 + 9x^3 + ... = g.f. for A002835 (solid partitions restricted to two planes) and expand (1-x)*(1-x^2)*(1-x^3)*...*F(x) in powers of x.at n=15A005980
- Expansion of (1-x^7)/(1-x)^7.at n=10A008489
- Numbers k such that the continued fraction for sqrt(k) has period 88.at n=14A020427
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 44 ones.at n=28A031812
- Number of subgroups of index 3 in fundamental group of a closed surface of characteristic -n.at n=6A049293
- Numbers n such that 147*2^n-1 is prime.at n=27A050599
- Numbers k such that 20*R_k + 9 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=8A056678
- Sum of squares of first n quarter-squares (A002620).at n=14A059859
- Number of cycles in range [A014137(n-1)..A014138(n-1)] of permutation A071663.at n=12A079441
- a(n) is the largest number such that all of a(n)'s length-n substrings are distinct and divisible by 33.at n=2A093233
- a(n) is the largest number such that all of a(n)'s length-n substrings are distinct and divisible by 66.at n=2A093266
- Numbers n such that n.s.rev(n) is palindromic and prime, where '.' represents concatenation, rev(n) is the reversal of n and s is the sum of n and rev(n). Or, n such that A084998(n) is prime.at n=2A093649
- Lesser of twin admirable numbers: k such that k and k+2 are both admirable numbers.at n=30A109730
- a(n) = 4*(n^2 - n + 1).at n=44A112087
- Number of partitions of n with no even parts repeated and with no 1's.at n=51A117275
- Number of nonisomorphic n-element self-dual posets (or partially ordered sets).at n=9A133983
- Numbers that are multiples of 28 and contain both a 4 and a 7.at n=26A171077
- Numbers k such that 12*k - 5, 12*k - 1, 12*k + 1, and 12*k + 5 are primes.at n=37A174372
- Numbers k such that (7*10^(2k+1) - 18*10^k - 7)/9 is prime.at n=10A183180
- Number of double rises in all left factors of Dyck paths of length n (a double rise consists of two consecutive (1,1)-steps).at n=13A191524