7639
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 25
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 7640
- 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
- 7638
- Möbius Function
- -1
- Radical
- 7639
- 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
- 31
- 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
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 969
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Number of rooted ternary trees with n nodes; number of n-carbon alkyl radicals C(n)H(2n+1) ignoring stereoisomers.at n=13A000598
- Convolution of odd numbers and A000201.at n=23A023658
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 87.at n=8A031585
- Upper prime of a difference of 18 between consecutive primes.at n=32A031937
- Numbers k such that 27*2^k+1 is prime.at n=27A032363
- Numbers whose base-4 representation contains exactly four 1's and three 3's.at n=13A045132
- First member of a prime triple in a 2p-1 progression.at n=37A057326
- Primes p such that x^67 = 2 has no solution mod p.at n=16A059330
- Smallest number such that GCD of EulerPhi of 2 consecutive integer equals 2n.at n=18A063444
- a(1) = 2, a(2) = 3 and a(n) = the smallest prime which is a linear combination of a(n-1) and a(n-2) of the form r*a(n-1) + s*a(n-2) with r,s >=1.at n=10A072535
- Primes p such that the number of distinct prime divisors of all composite numbers between p and the next prime is 6.at n=39A075586
- Sums of groups in A075635.at n=22A075636
- Primes in which odd positioned digits are composite and even positioned digits are primes. The least significant digit is the taken to be the first digit.at n=23A083821
- Primes which are also prime if their base 19 representation is interpreted as a base 10 number.at n=41A090714
- Primes arising as the arithmetic mean of first n terms of A090918.at n=44A090919
- Primes of the form 23n+3.at n=42A100201
- Primes of the form Sum_{k=1..n} phi(prime(k)).at n=12A101302
- Primes with digit sum = 25.at n=37A106763
- Primes p such that p^3 is a sum of three successive primes, or primes in A076306(n).at n=40A123984
- Number of bicyclic skeletons with n carbon atoms and the parameter 'alpha' having the value of 2. See the paper by Hendrickson and Parks for details.at n=8A125671