# What's special about these numbers?

-1 is the only number which only 1 and itself divide it to give an integer that is not considered a prime.
1 is the multiplicative and divisive identity.
6 is the smallest perfect number.
41 is a value of n so that x^2 + x + n takes on prime values for x = 0, 1, 2, ... n-2.
53 is the only 2-digit number that is reversed is hexadecimal.
57=111 in base 7.
50 is the smallest number that can be written as the sum of 2 squares of positive numbers in 2 ways (7^2+1^2 and 5^2+5^2). 64 is the smallest number with 7 divisors.
129 is the smallest number that can be written as a sum of 3 squares of positive numbers in at least 4 ways (11^2+2^2+2^2, 10^2 + 5^2 +2^2, 8^2+8^2+1^2 and 8^2+7^2+4^2)
150 can be represented as 10010110 is base 2, 2112 in base 4 and 1100 in base 5. It also uses 2 digits an equal amount of times.

Note by Ken Kai
7 months, 3 weeks ago

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