how to interrogate BigNumber words?

Question

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
import "@openzeppelin/contracts/utils/Counters.sol";

contract GameItem is ERC721URIStorage {
    using Counters for Counters.Counter;
    Counters.Counter private _tokenIds;

    constructor() ERC721("GameItem", "ITM") {}

    function awardItem(address player, string memory tokenURI)
        public
        returns (uint256)
    {
        _tokenIds.increment();

        uint256 newItemId = _tokenIds.current();
        _mint(player, newItemId);
        _setTokenURI(newItemId, tokenURI);

        return newItemId;
    }
}

I have an ERC721 contract and have awarded some tokens to an address. Just playing around in truffle querying the contract.. but having a problem wit balanceOf..

truffle(development)> x = instance.balanceOf('0x295A360036B71cd1223e11EDEC2903913BfC6a63')
BN { negative: 0, words: [ 4, <1 empty item> ], length: 1, red: null }
truffle(development)> x.words[0]
evalmachine.<anonymous>:0
x.words[0]
       ^
Uncaught TypeError: Cannot read property '0' of undefined
    at evalmachine.<anonymous>:0:8
    at sigintHandlersWrap (vm.js:273:12)
    at Script.runInContext (vm.js:142:14)
    at runScript (/Users/xxx/.nvm/versions/node/v14.17.4/lib/node_modules/truffle/build/webpack:/packages/core/lib/console.js:364:1)
    at Console.interpret (/Users/xxx/.nvm/versions/node/v14.17.4/lib/node_modules/truffle/build/webpack:/packages/core/lib/console.js:379:1)
    at bound (domain.js:416:15)
    at REPLServer.runBound [as eval] (domain.js:427:12)
    at REPLServer.onLine (repl.js:821:10)
    at REPLServer.emit (events.js:400:28)
    at REPLServer.emit (domain.js:470:12)

how can I read the 'words' ?