128138587 has 4 divisors (see below), whose sum is σ = 128165416. Its totient is φ = 128111760.

The previous prime is 128138573. The next prime is 128138611. The reversal of 128138587 is 785831821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 785831821 = 29 ⋅27097649.

It is a cyclic number.

It is not a de Polignac number, because 128138587 - 2⁷ = 128138459 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128138557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4089 + ... + 16522.

It is an arithmetic number, because the mean of its divisors is an integer number (32041354).

Almost surely, 2^128138587 is an apocalyptic number.

128138587 is a deficient number, since it is larger than the sum of its proper divisors (26829).

128138587 is an equidigital number, since it uses as much as digits as its factorization.

128138587 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26828.

The product of its digits is 107520, while the sum is 43.

The square root of 128138587 is about 11319.8315800192. The cubic root of 128138587 is about 504.1502383949.

The spelling of 128138587 in words is "one hundred twenty-eight million, one hundred thirty-eight thousand, five hundred eighty-seven".