128 is the natural number following 127 and preceding 129.

One hundred twenty-eight is the largest number which can not be expressed as the sum of any number of distinct squares. But it can be expressed combining its digits with mathematical operators thus 128 = 2^8-1, making it a Friedman number.

One hundred twenty-eight is also:

• The size, in bits, of certain integer data types, used in computer representations of numbers.
• The number of sons of Anathoth at the Census of men of Israel upon return from exile (Holy Bible, Ezra 2:23). Also, the number of singers, sons of Asaph (Ezra 2:41).
• In megabytes, a common size for flash disks and memory cards.
• The number of musical instruments specified in General MIDI. Sometimes they are numbered 0 to 127 and sometimes they are numbered 1 to 128.
• When counting in binary with fingers, expressing 128 as 0000000100, results in the isolation of the middle finger on one hand, a gesture generally considered rude.
• The year 128.