Euler's phi function

GPTKB entity

Statements (24)
Predicate Object
gptkbp:instanceOf arithmetic function
gptkbp:alsoKnownAs gptkb:Euler's_totient_function
gptkbp:codomain non-negative integers
gptkbp:defines number of positive integers up to n that are coprime to n
gptkbp:domain positive integers
gptkbp:firstFewValues φ(1)=1, φ(2)=1, φ(3)=2, φ(4)=2, φ(5)=4, φ(6)=2, φ(7)=6, φ(8)=4, φ(9)=6, φ(10)=4
gptkbp:form φ(n) = n ∏_{p|n} (1 - 1/p)
https://www.w3.org/2000/01/rdf-schema#label Euler's phi function
gptkbp:introduced gptkb:Leonhard_Euler
gptkbp:introducedIn 1763
gptkbp:multiplicative true
gptkbp:namedAfter gptkb:Leonhard_Euler
gptkbp:property φ(mn) = φ(m)φ(n) if gcd(m, n) = 1
sum_{d|n} φ(d) = n
n = ∑_{d|n} φ(d)
gptkbp:sequence gptkb:A000010_(OEIS)
gptkbp:symbol φ(n)
gptkbp:usedIn gptkb:RSA_algorithm
cryptography
number theory
gptkbp:valueAtPrime φ(p) = p - 1 for prime p
gptkbp:valueAtPrimePower φ(p^k) = p^k - p^{k-1}
gptkbp:bfsParent gptkb:Euler's_totient_function_φ(n)
gptkbp:bfsLayer 6