15121
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 10
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 15122
- 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
- 15120
- Möbius Function
- -1
- Radical
- 15121
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 84
- 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
- 1766
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Integer part of 24(2^n-1)/n.at n=12A003176
- Expansion of e.g.f. cos(x*exp(x)).at n=8A009017
- Primes of the form k^2 - 8.at n=28A028886
- Smallest prime containing n-th cube as substring.at n=8A029949
- Smallest prime of form (n!)*k + 1.at n=6A035094
- Primes resulting from procedure described in A048393.at n=21A048394
- Minimal factorial safe-primes: a prime p = a(n) here if (p-1)/n! = A051888(n).at n=7A051901
- Second term of strong prime 5-tuples: p(m)-p(m-1) > p(m+1)-p(m) > p(m+2)-p(m+1) > p(m+3)-p(m+2).at n=34A054809
- Primes p such that x^16 = 2 has no solution mod p, but x^8 = 2 has a solution mod p.at n=32A059287
- Primes of the form 3*k! + 1.at n=4A062551
- Primes p such that (x1*x2*...*xk)^(x1+x2+...+xk) = (x1+x2+...+xk)^(x1*x2*...*xk) where x1x2...xk are the digits of p in base 10.at n=10A064157
- Prime numbers such that sum of digits equals product of digits.at n=9A066306
- Numbers k > 1 such that sigma(phi(k))/sigma(k) > sigma(phi(j))/sigma(j) for all 1 < j < k.at n=19A067573
- Centered 24-gonal numbers.at n=35A069190
- Primes p such that x^8 = 2 has a solution mod p, but x^(8^2) = 2 has no solution mod p.at n=38A070184
- Primes p such that p-1 is a highly composite number.at n=11A072826
- Smallest start for a run of n consecutive numbers of which the i-th has exactly i prime factors.at n=4A072875
- Primes of the form 210n + 1.at n=33A073102
- Smallest prime == 1 mod first n composite numbers.at n=9A075063
- Smallest prime == 1 mod first n composite numbers.at n=8A075063