128135521920 has 128 divisors (see below), whose sum is σ = 466779450240. Its totient is φ = 29288116224.

The previous prime is 128135521901. The next prime is 128135521933. The reversal of 128135521920 is 29125531821.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (128).

It is an unprimeable number.

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, 4753507 + ... + 4780386.

It is an arithmetic number, because the mean of its divisors is an integer number (3646714455).

Almost surely, 2^128135521920 is an apocalyptic number.

128135521920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

128135521920 is an abundant number, since it is smaller than the sum of its proper divisors (338643928320).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

128135521920 is an equidigital number, since it uses as much as digits as its factorization.

128135521920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9533922 (or 9533910 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 39.

Subtracting from 128135521920 its reverse (29125531821), we obtain a palindrome (99009990099).

The spelling of 128135521920 in words is "one hundred twenty-eight billion, one hundred thirty-five million, five hundred twenty-one thousand, nine hundred twenty".