128000821 has 4 divisors (see below), whose sum is σ = 137847052. Its totient is φ = 118154592.

The previous prime is 128000813. The next prime is 128000827.

128000821 is nontrivially palindromic in base 10.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 39828721 + 88172100 = 6311^2 + 9390^2 .

It is a cyclic number.

It is not a de Polignac number, because 128000821 - 2³ = 128000813 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 128000792 and 128000801.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128000827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4923096 + ... + 4923121.

It is an arithmetic number, because the mean of its divisors is an integer number (34461763).

Almost surely, 2^128000821 is an apocalyptic number.

It is an amenable number.

128000821 is a deficient number, since it is larger than the sum of its proper divisors (9846231).

128000821 is an equidigital number, since it uses as much as digits as its factorization.

128000821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9846230.

The product of its (nonzero) digits is 256, while the sum is 22.

The square root of 128000821 is about 11313.7447823433. The cubic root of 128000821 is about 503.9694974506.

It can be divided in two parts, 128000 and 821, that added together give a palindrome (128821).

The spelling of 128000821 in words is "one hundred twenty-eight million, eight hundred twenty-one", and thus it is an aban number.