How do I make a discord.js random number generator that generates off user input

How do I make a discord.js random number generator that generates off user input? I've been trying to do this for a long time but just cant get anything to work with my format of code.

if (message.content == "<lottery") {
   let embed = new Discord.MessageEmbed()
   .setTitle("**Lottery Winner!**")
   .setDescription("The winner of the lottery's number is {The random number that is generated")
   .setColor("RANDOM")
   .setFooter(`Congratulations!`)
   .setThumbnail('https://cdn.discordapp.com/attachments/800757031506149426/835360163782459422/OIP.png')
   message.channel.send(embed);
}``` How do I somehow get the rng inside that embed?