Factors of Mersenne Number M67

Theorem
The Mersenne number $M_{67}$ has the factors:
 * $193 \, 707 \, 721$
 * $761 \, 838 \, 257 \, 287$

Proof
193 707 721         x 761 838 257 287 --             1 355 954 047             15 496 617 680             38 741 544 200          1 355 954 047 000          9 685 386 050 000         38 741 544 200 000      1 549 661 768 000 000      5 811 231 630 000 000    154 966 176 800 000 000    193 707 721 000 000 000 11 622 463 260 000 000 000 135 595 404 700 000 000 000 --- 147 573 952 579 676 412 927 ---  1 223 254 435 432 22  1

2^2 = 4

2^4 = 4 x 4 = 16

2^8 = 16 x 16 = 256

2^16 = 256 x 256 = 65536

256 x 256 -- 1 536 12 800 51 200 -- 65 536 --

65 536    x 65 536 -      393 216    1 966 080   32 768 000  327 680 000 3 932 160 000 - 4 924 967 296 -

4 294 967 296           x 4 294 967 296 ---            25 769 803 776            386 547 056 640            858 993 459 200         30 064 771 072 000 etc. WIP

2^32 = 4 294 967 296

2^64 = 18 446 744 073 709 551 616

2^67 = 2^64 x 2^3

Historical Note
This demonstration was made by who performed the arithmetic, longhand, on a blackboard in a famously wordless lecture in 1903.