128155551821 has 16 divisors (see below), whose sum is σ = 140406583680. Its totient is φ = 116005048320.

The previous prime is 128155551803. The next prime is 128155551833.

128155551821 is nontrivially palindromic in base 10.

It is a cyclic number.

It is not a de Polignac number, because 128155551821 - 2¹⁰ = 128155550797 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128155551851) 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 15 ways as a sum of consecutive naturals, for example, 6566045 + ... + 6585533.

It is an arithmetic number, because the mean of its divisors is an integer number (8775411480).

Almost surely, 2^128155551821 is an apocalyptic number.

128155551821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

128155551821 is a deficient number, since it is larger than the sum of its proper divisors (12251031859).

128155551821 is a wasteful number, since it uses less digits than its factorization.

128155551821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22036.

The product of its digits is 160000, while the sum is 44.

It can be divided in two parts, 128155 and 551821, that added together give a palindrome (679976).

The spelling of 128155551821 in words is "one hundred twenty-eight billion, one hundred fifty-five million, five hundred fifty-one thousand, eight hundred twenty-one".