7643
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 7644
- 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
- 7642
- Möbius Function
- -1
- Radical
- 7643
- 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
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- yes
- Safe Prime
- yes
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 970
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- 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=9A031585
- Number of ordered positive integer solutions (m_1, m_2, ..., m_k) (for some k) to Sum_{i=1..k} m_i=n with |m_i-m_{i-1}| <= 1 for i = 2 ... k.at n=18A034297
- Primes with distinct digits in descending order.at n=37A052014
- Safe primes which are also Sophie Germain primes.at n=26A059455
- Emirps which when concatenated with their reversals after a 0 make a palindromic prime of the form emirp0prime.at n=31A070954
- a(1)=1; a(n) = a(n-1) + [sum of all decimal digits present so far in the sequence].at n=37A072921
- a(0) = 2; a(n) for n > 0 is the smallest prime greater than a(n-1) that differs from a(n-1) by a square.at n=33A073609
- Primes p such that sum of even digits of p equals sum of odd digits of p.at n=33A076167
- Balanced primes of order three.at n=43A082078
- a(n) = (prime(n)+1)*n - 1.at n=41A083723
- First occurrence of primes in the progression k*x^2-1.at n=34A090688
- Continued fraction expansion for phi^phi, where phi is the golden ratio (1+sqrt(5))/2.at n=11A092134
- Primes which are the sum of a twin prime pair - 1.at n=32A118072
- Primes p such that 2*p+1 and 2*p+3 are twin primes.at n=35A126107
- Primes p such that q = p+d (with d >= 6) is the next prime and both p and q are Sophie Germain primes.at n=22A128825
- Father primes of order 6.at n=38A136075
- Primes of the form 3x^2+440y^2.at n=33A139999
- Primes of the form 3x^2+455y^2.at n=28A140015
- Primes congruent to 83 or 127 mod 210.at n=39A140771
- Primes of the form 2*3*5*7*n+83.at n=17A141570