128804521 has 4 divisors (see below), whose sum is σ = 129067344. Its totient is φ = 128541700.

The previous prime is 128804491. The next prime is 128804539. The reversal of 128804521 is 125408821.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 128804521 - 2¹¹ = 128802473 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128804321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 130675 + ... + 131656.

It is an arithmetic number, because the mean of its divisors is an integer number (32266836).

Almost surely, 2^128804521 is an apocalyptic number.

It is an amenable number.

128804521 is a deficient number, since it is larger than the sum of its proper divisors (262823).

128804521 is an equidigital number, since it uses as much as digits as its factorization.

128804521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 262822.

The product of its (nonzero) digits is 5120, while the sum is 31.

The square root of 128804521 is about 11349.2079459317. The cubic root of 128804521 is about 505.0220831437.

The spelling of 128804521 in words is "one hundred twenty-eight million, eight hundred four thousand, five hundred twenty-one".