Natural number
129 (one hundred [and] twenty-nine ) is thenatural number following128 and preceding130 .
129 is the sum of the first tenprime numbers . It is the smallest number that can be expressed as a sum of three squares in four different ways:11 2 + 2 2 + 2 2 {\displaystyle 11^{2}+2^{2}+2^{2}} 10 2 + 5 2 + 2 2 {\displaystyle 10^{2}+5^{2}+2^{2}} 8 2 + 8 2 + 1 2 {\displaystyle 8^{2}+8^{2}+1^{2}} 8 2 + 7 2 + 4 2 {\displaystyle 8^{2}+7^{2}+4^{2}}
129 is the product of only two primes, 3 and 43, making 129 asemiprime . Since 3 and 43 are bothGaussian primes , this means that 129 is aBlum integer .[ 1]
129 is arepdigit in base 6 (333).
129 is ahappy number .[ 2]
129 is acentered octahedral number .[ 3]
400 to 999
400s, 500s, and 600s 700s, 800s, and 900s
1000s and 10,000s
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100,000s to 10,000,000,000,000s
100,000 1,000,000 10,000,000 100,000,000 1,000,000,000 10,000,000,000 100,000,000,000 1,000,000,000,000 10,000,000,000,000
