646 = 2 x 17 x 19.
646 is a divisor of 696 - 1.
646 is the number of connected planar graphs with 7 vertices (A003094).
646 is 787 in base 9.
646 is the sum of seven positive fifth powers: 646 = 35 + 35 + 25 + 25 + 25 + 25 + 25.
Source: What's Special About This Number?
1 comment:
I'm sorry - I can't help but comment. What's special about 646? - it's the hull number of one great (former) submarine: USS GRAYLING (SSN 646) - Fast Attack Tough!! :-)
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