128888821 has 4 divisors (see below), whose sum is σ = 130337100. Its totient is φ = 127440544.

The previous prime is 128888813. The next prime is 128888839.

128888821 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 78322500 + 50566321 = 8850^2 + 7111^2 .

It is a cyclic number.

It is not a de Polignac number, because 128888821 - 2³ = 128888813 is a prime.

It is a super-2 number, since 2×128888821² = 33224656357540082, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128888801) 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, 724006 + ... + 724183.

It is an arithmetic number, because the mean of its divisors is an integer number (32584275).

Almost surely, 2^128888821 is an apocalyptic number.

It is an amenable number.

128888821 is a deficient number, since it is larger than the sum of its proper divisors (1448279).

128888821 is an equidigital number, since it uses as much as digits as its factorization.

128888821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1448278.

The product of its digits is 131072, while the sum is 46.

The square root of 128888821 is about 11352.9212540209. The cubic root of 128888821 is about 505.1322347565.

It can be divided in two parts, 1288 and 88821, that added together give a palindrome (90109).

The spelling of 128888821 in words is "one hundred twenty-eight million, eight hundred eighty-eight thousand, eight hundred twenty-one".