[Ethereum] Cannot read property ‘call’ of undefined

I am running HelloWorld contract.

pragma solidity ^0.4.2;
contract HelloWorld {
    uint public balance;

    function Helloworld(){
        balance = 1000;
    }
}

After truffle compile and truffle migrate command I ran below command in truffle console:

HelloWorld.balance.call()

Error:

TypeError: Cannot read property 'call' of undefined
at evalmachine.:1:19
at ContextifyScript.Script.runInContext (vm.js:35:29)
at Object.exports.runInContext (vm.js:67:17)
at TruffleInterpreter.interpret (/usr/lib/node_modules/truffle/lib/repl.js:99:17)
at bound (domain.js:280:14)
at REPLServer.runBound [as eval] (domain.js:293:12)
at REPLServer. (repl.js:545:10)
at emitOne (events.js:96:13)
at REPLServer.emit (events.js:188:7)
at REPLServer.Interface._onLine (readline.js:239:10)

truffle(default)> HelloWorld.deployed()
Contract {
  contract:
   Contract {
     _eth:
      Eth {
        _requestManager: [Object],
        getBalance: [Object],
        getStorageAt: [Object],
        getCode: [Object],
        getBlock: [Object],
        getUncle: [Object],
        getCompilers: [Object],
        getBlockTransactionCount: [Object],
        getBlockUncleCount: [Object],
        getTransaction: [Object],
        getTransactionFromBlock: [Object],
        getTransactionReceipt: [Object],
        getTransactionCount: [Object],
        call: [Object],
        estimateGas: [Object],
        sendRawTransaction: [Object],
        sendTransaction: [Object],
        sign: [Object],
        compile: [Object],
        submitWork: [Object],
        getWork: [Object],
        coinbase: [Getter],
        getCoinbase: [Object],
        mining: [Getter],
        getMining: [Object],
        hashrate: [Getter],
        getHashrate: [Object],
        syncing: [Getter],
        getSyncing: [Object],
        gasPrice: [Getter],
        getGasPrice: [Object],
        accounts: [Getter],
        getAccounts: [Object],
        blockNumber: [Getter],
        getBlockNumber: [Object],
        iban: [Object],
        sendIBANTransaction: [Function: bound transfer] },
     transactionHash: null,
     address: '0x83367f99f17e89248c32f4a323c027446246e650',
     abi: [ [Object], [Object] ],
     Helloworld:
      { [Function: bound ]
        request: [Function: bound ],
        call: [Function: bound ],
        sendTransaction: [Function: bound ],
        estimateGas: [Function: bound ],
        getData: [Function: bound ],
        '': [Circular] },
     balance:
      { [Function: bound ]
        request: [Function: bound ],
        call: [Function: bound ],
        sendTransaction: [Function: bound ],
        estimateGas: [Function: bound ],
        getData: [Function: bound ],
        '': [Circular] },
     allEvents: [Function: bound ] },
  Helloworld:
   { [Function]
     call: [Function],
     sendTransaction: [Function],
     request: [Function: bound ],
     estimateGas: [Function] },
  balance:
   { [Function]
     call: [Function],
     sendTransaction: [Function],
     request: [Function: bound ],
     estimateGas: [Function] },
  allEvents: [Function: bound ],
  address: '0x83367f99f17e89248c32f4a323c027446246e650',
  transactionHash: null }