128780928 has 80 divisors (see below), whose sum is σ = 383280810. Its totient is φ = 42923520.

The previous prime is 128780923. The next prime is 128780941. The reversal of 128780928 is 829087821.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 75898944 + 52881984 = 8712^2 + 7272^2 .

It is not an unprimeable number, because it can be changed into a prime (128780923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 4158 + ... + 16578.

Almost surely, 2^128780928 is an apocalyptic number.

128780928 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 128780928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (191640405).

128780928 is an abundant number, since it is smaller than the sum of its proper divisors (254499882).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

128780928 is an equidigital number, since it uses as much as digits as its factorization.

128780928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12447 (or 12426 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 45.

The square root of 128780928 is about 11348.1684865885. The cubic root of 128780928 is about 504.9912464581.

It can be divided in two parts, 1287 and 80928, that added together give a triangular number (82215 = T₄₀₅).

The spelling of 128780928 in words is "one hundred twenty-eight million, seven hundred eighty thousand, nine hundred twenty-eight".