The $5,150 standard deduction was already factored into my tax calculations.
Your tax liability before ANY withholding was $10,001, They withheld $4,000 from the 401K distribution, so your tax withholding from your salary has to cover $6,000. Not likely.
Your tax bill will be the difference between what your total federal income tax withholding was and $6,000. Since you have not told what was withheld from your pay, I cannot answer for sure what you will have to pay when you file tax return.
However, based on what you HAVE told me, I think your annual withodling is about $4,000. If I am right, you will have to pay about $2,000 when you file your tax return.
If I were you, I would start saving right now. You have until April 15th to collect the money to pay the tax bill. Otherwise, you will have to pay on a payment plan.