• 128 can be written using four 4's:

See also 113.

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128 has 8 divisors (see below), whose sum is σ = 255. Its totient is φ = 64.

The previous prime is 127. The next prime is 131. The reversal of 128 is 821.

It is a perfect power (a 7-th power), and thus also a powerful number.

It is a Jordan-Polya number, since it can be written as (2!)⁷.

128 is nontrivially palindromic in base 7 and base 15.

It can be written as a sum of positive squares in only one way, i.e., 64 + 64 = 8^2 + 8^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=8.

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is one of the 548 Lynch-Bell numbers.

It is a Duffinian number.

128 is an undulating number in base 7.

Its product of digits (16) is a multiple of the sum of its prime divisors (2).

128 is a nontrivial repdigit in base 15.

It is a plaindrome in base 10, base 13 and base 15.

It is a nialpdrome in base 2, base 4, base 6, base 8, base 12, base 14, base 15 and base 16.

It is a zygodrome in base 15.

In principle, a polygon with 128 sides can be constructed with ruler and compass.

It is an impolite number, since it cannot be written as a nontrivial sum of consecutive naturals.

128 is a Friedman number, since it can be written as 2^(8-1), using all its digits and the basic arithmetic operations.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 128

128 is a deficient number, since it is larger than the sum of its proper divisors (127).

128 is an frugal number, since it uses more digits than its factorization.

128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14 (or 2 counting only the distinct ones).

The product of its digits is 16, while the sum is 11.

The square root of 128 is about 11.3137084990. The cubic root of 128 is about 5.0396841996.

Adding to 128 its product of digits (16), we get a square (144 = 12²).

Multiplying 128 by its product of digits (16), we get a 11-th power (2048 = 2¹¹).

Adding to 128 its reverse (821), we get a palindrome (949).

The spelling of 128 in words is "one hundred twenty-eight", and thus it is an aban number.