128646646821 has 128 divisors (see below), whose sum is σ = 253583032320. Its totient is φ = 62400844800.

The previous prime is 128646646811. The next prime is 128646646847.

128646646821 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 128646646821 - 2⁶ = 128646646757 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128646646811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 4474231 + ... + 4502891.

It is an arithmetic number, because the mean of its divisors is an integer number (1981117440).

Almost surely, 2^128646646821 is an apocalyptic number.

128646646821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

128646646821 is a deficient number, since it is larger than the sum of its proper divisors (124936385499).

128646646821 is a wasteful number, since it uses less digits than its factorization.

128646646821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28832 (or 28826 counting only the distinct ones).

The product of its digits is 5308416, while the sum is 54.

The spelling of 128646646821 in words is "one hundred twenty-eight billion, six hundred forty-six million, six hundred forty-six thousand, eight hundred twenty-one".