The information in this preliminary pricing supplement is not complete and may be changed. This preliminary pricing supplement is not an offer to sell these securities in any jurisdiction where the offer or sale is not permitted.

Subject to completion dated June 16, 2025

Filed under Rule 424(b)(3), Registration Statement No. 333-275151

Pricing Supplement No. 21 - Dated Monday, June 16, 2025 (To: Prospectus Dated October 24, 2023 and Prospectus Supplement Dated November 1, 2024)

CUSIP Number

Principal Amount

Selling Price

Gross Concession

Net Proceeds

Coupon Type

Coupon Rate

Coupon Frequency

Maturity Date

1st Coupon Date

1st Coupon Amount

Survivor's Option

Product Ranking

63743LAW3

[ ]

100.000%

3.150%

[ ]

Fixed

5.750%

Semi- Annual

06/15/2055

12/15/2025

$26.99

Yes

Subordinated Notes

Redemption Information:

Callable at the Issuer’s option, in whole or from time to time in part, on any day on or after 06/15/2030 (the “Par Call Period”) at a redemption price in cash equal to 100% of the principal amount of the notes being redeemed, plus, accrued and unpaid interest, if any, thereon to, but excluding, the redemption date

	Offering Date: Monday, June 16, 2025 through Monday, June 23, 2025	National Rural Utilities Cooperative Finance Corp
National Rural Utilities Cooperative Finance Corp	Trade Date: Monday, June 23, 2025 @12:00 PM ET	Subordinated Notes (Subordinated Deferrable Interest Notes)
	Settle Date: Thursday, June 26, 2025
	Minimum Denomination/Increments:$1,000.00/$1,000.00	Prospectus dated October 24, 2023 and
	Initial trades settle flat and clear SDFS: DTC Book Entry only	Prospectus Supplement Dated: November 1, 2024
	DTC Number: 0235 via RBC Dain Rauscher Inc.
	Agents: InspereX LLC, Citigroup Global Markets Inc., RBC Capital Markets, LLC, Wells Fargo Clearing Services, LLC
	Trustee: U.S. Bank Trust Company, National Association