My first combinatorics' problem

Jane is a computer security expert and works as an ethical hacker for a leading global institute. Therefore she has to be extremely secure as her passwords are keys to billions of dollars. She is choosing a secret passcode consisting of the digits $\text{1,2,...,p}$ for some $p$ . She would like her passcode to use each digit at most once and because she is concerned about security, she would like to choose a value of $p$ such that the number of possible permutations is at least 450 million so that even by using brute-force methods, it won't be easy. What is the smallest value of $p$ Jane can use?