From the IRS’s Form 1040-ES instructions:
No checks of $100 million or more accepted. The IRS can’t accept a single check (including a cashier’s check) for amounts of $100,000,000 ($100 million) or more. If you are sending $100 million or more by check, you will need to spread the payment over 2 or more checks with each check made out for an amount less than $100 million. This limit doesn’t apply to other methods of payment (such as electronic payments). Please consider a method of payment other than check if the amount of the payment is over $100 million.