# 8128 (number)

8128 is the integer following 8127 and preceding 8129.

 ← 8127 8128 8129 →
Cardinaleight thousand one hundred twenty-eight
Ordinal8128th
(eight thousand one hundred twenty-eighth)
Factorization26× 127
Divisors1, 2, 4, 8, 16, 32, 64, 127, 254, 508, 1016, 2032, 4064
Greek numeral,ΗΡΚΗ´
Roman numeralVMMMCXXVIII
Binary11111110000002
Ternary1020110013
Quaternary13330004
Quinary2300035
Senary1013446
Octal177008
Duodecimal485412
Vigesimal106820
Base 3669S36

It is most notable for being a perfect number, and one of the earliest numbers to be recognized as such. As a perfect number, it is tied to the Mersenne prime 127, 27 – 1, with 26 (27 – 1) yielding 8128. Also related to its being a perfect number, 8128 is a harmonic divisor number.[1]

Another consequence of 8128 being a perfect number is that it has the same prime factors as the sum of its divisors, its cototient is a power of two, and it is a harmonic seed number (though there are deficient and abundant numbers that share these properties).

8128 is the 127th triangular number, the 64th hexagonal number, a happy number, the eighth 292-gonal number, and the fourth 1356-gonal number, as well as the 43rd centered nonagonal number.[2]