220,000

[EECS]  220K(W) is one of standard numerical values for resistors (of tolerance class 5%).

221,089

[Math.]   108,878,221,089 = (108878+221089)2 = 3299672 and

448,944,221,089 = (448944+221089)2 = 670,0332 and 329967+670033 = 1,000,000.

221,430

[Math.]  Two consecutive sums of consecutive numbers: 3600+…+3660 = 3661+…+3720 = 221,430.

222,111

[Math.]  A triangular number (sum of all integers from 1 to 666):  222,111 = 1+2+…+665+666.

222,222

[Math.]  All the cubic powers 23 = 8, 223 = 10,648, 2223 = 10,941,048, 22223 = 10,970,645,048, 22,2223 = 10,973,607,685,048 and 222,2223 = 10,973,903,978,085,048 do not use digits 2.

[Trivia]  From two to two to two two” means the period of 4 minutes from 1:58 to 2:02.

223,729

[Math.]  Square and 4th power of number 473 use different digits: 4732 = 223,729 and 4734 = 50,054,665,441.

224,737

[Math.]  The 20,000th prime number.

227,904

[Math.]   123,448,227,904 = (123,448+227,904)2 = 351,3522  and

420,744,227,904 = (420,744+227,904)2 = 648,6482 and 351352+648648 = 1,000,000.

229,449

[Math.]  127,194,229,449 = (127194+229449)2 = 356,6432 and

413,908,229,449 = (413908+229449)2 = 643,3572 and 356,643+643357 = 1,000,000.