Recover the prime from the prime power

Question

Definition: a prime power is a natural number that can be expressed in the form pⁿ where p is a prime and n is a natural number.

Task: Given a prime power pⁿ > 1, return the prime p.

Testcases:

input output
9     3
16    2
343   7
2687  2687
59049 3

Scoring: This is code-golf. Shortest answer in bytes wins.

Answer 1

Pari/GP, 17 bytes

n->factor(n)[1,1]

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Pari/GP, 17 bytes

n->divisors(n)[2]

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Answer 2

Ruby, 100 bytes

require"prime"
i=gets.to_i
Prime.each(i){|p|(1..i).each{|n|c=p**n==i
    puts p if c
    exit if c}}

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Answer 3

Stax, 3 bytes

|fh

Run and debug it

First element of prime factorization.

Answer 4

Julia 0.6, 25 bytes

n->[2:n;][n.%(2:n).<1][1]

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Answer 5

Ruby, 26 bytes

->n,i=1{(1>n%i+=1)?i:redo}

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Answer 6

QBasic, 39 bytes

INPUT x
p=2
WHILE x\p<x/p
p=p+1
WEND
?p

Trial division; finds the first factor greater than 1, which is guaranteed to be the prime factor.

The only trick here is the condition x\p<x/p, which uses integer vs. floating point division to test whether "x is not divisible by p." See this tip for details.