128531135821 has 4 divisors (see below), whose sum is σ = 140215784544. Its totient is φ = 116846487100.

The previous prime is 128531135767. The next prime is 128531135827.

It is a happy number.

128531135821 is nontrivially palindromic in base 10.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 128531135821 - 2⁷ = 128531135693 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128531135827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5842324345 + ... + 5842324366.

It is an arithmetic number, because the mean of its divisors is an integer number (35053946136).

Almost surely, 2^128531135821 is an apocalyptic number.

128531135821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

128531135821 is a deficient number, since it is larger than the sum of its proper divisors (11684648723).

128531135821 is a wasteful number, since it uses less digits than its factorization.

128531135821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11684648722.

The product of its digits is 57600, while the sum is 40.

The spelling of 128531135821 in words is "one hundred twenty-eight billion, five hundred thirty-one million, one hundred thirty-five thousand, eight hundred twenty-one".