128805508821 has 16 divisors (see below), whose sum is σ = 187360842240. Its totient is φ = 78060871920.

The previous prime is 128805508789. The next prime is 128805508847.

128805508821 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 128805508821 - 2⁵ = 128805508789 is a prime.

It is a super-3 number, since 3×128805508821³ (a number of 34 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128805508861) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 999166 + ... + 1120688.

It is an arithmetic number, because the mean of its divisors is an integer number (11710052640).

Almost surely, 2^128805508821 is an apocalyptic number.

128805508821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

128805508821 is a deficient number, since it is larger than the sum of its proper divisors (58555333419).

128805508821 is a wasteful number, since it uses less digits than its factorization.

128805508821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153656.

The product of its (nonzero) digits is 409600, while the sum is 48.

The spelling of 128805508821 in words is "one hundred twenty-eight billion, eight hundred five million, five hundred eight thousand, eight hundred twenty-one".