128321557 has 16 divisors (see below), whose sum is σ = 159344640. Its totient is φ = 100622592.

The previous prime is 128321551. The next prime is 128321597. The reversal of 128321557 is 755123821.

It is not a de Polignac number, because 128321557 - 2⁷ = 128321429 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128321551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4044 + ... + 16522.

It is an arithmetic number, because the mean of its divisors is an integer number (9959040).

Almost surely, 2^128321557 is an apocalyptic number.

It is an amenable number.

128321557 is a deficient number, since it is larger than the sum of its proper divisors (31023083).

128321557 is a wasteful number, since it uses less digits than its factorization.

128321557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12612.

The product of its digits is 16800, while the sum is 34.

The square root of 128321557 is about 11327.9105310732. The cubic root of 128321557 is about 504.3900841760.

The spelling of 128321557 in words is "one hundred twenty-eight million, three hundred twenty-one thousand, five hundred fifty-seven".