12157
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 12158
- Proper Divisor Sum (Aliquot Sum)
- 1
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 12156
- Möbius Function
- -1
- Radical
- 12157
- 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
- 156
- 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
- 1455
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = (Lucas numbers), t = (primes).at n=19A024478
- Duplicate of A024478.at n=19A025090
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = (Lucas numbers), t = (primes).at n=18A025098
- Primes that are palindromic in base 7.at n=37A029975
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 52 ones.at n=35A031820
- Base-7 palindromes that start with 5.at n=19A043019
- Primes at which the difference pattern X42Y (X and Y >= 6) occurs in A001223.at n=28A052164
- Group the natural numbers so that the n-th group contains n numbers whose sum as well as the group product +1 is prime. Sequence contains the primes arising as the sum of the terms of groups.at n=28A092946
- List the first term of each triple of consecutive primes with the property that their sum is the square of a prime.at n=7A130621
- Primes congruent to 21 mod 37.at n=34A142130
- Primes congruent to 21 mod 41.at n=30A142218
- Primes congruent to 31 mod 43.at n=35A142280
- Primes congruent to 31 mod 47.at n=32A142382
- Primes congruent to 5 mod 49.at n=39A142418
- Primes congruent to 20 mod 53.at n=25A142550
- Primes congruent to 2 mod 55.at n=37A142602
- Primes congruent to 16 mod 57.at n=35A142675
- Primes congruent to 3 mod 59.at n=22A142730
- Primes congruent to 18 mod 61.at n=23A142816
- Primes congruent to 61 mod 63.at n=39A142923