7128897891 has 4 divisors (see below), whose sum is σ = 9505197192. Its totient is φ = 4752598592.

The previous prime is 7128897833. The next prime is 7128897899. The reversal of 7128897891 is 1987988217.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 7128897891 - 2⁹ = 7128897379 is a prime.

It is not an unprimeable number, because it can be changed into a prime (7128897899) 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, 1188149646 + ... + 1188149651.

It is an arithmetic number, because the mean of its divisors is an integer number (2376299298).

Almost surely, 2^7128897891 is an apocalyptic number.

7128897891 is a deficient number, since it is larger than the sum of its proper divisors (2376299301).

7128897891 is a wasteful number, since it uses less digits than its factorization.

7128897891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2376299300.

The product of its digits is 4064256, while the sum is 60.

The square root of 7128897891 is about 84432.8010372746. The cubic root of 7128897891 is about 1924.6014031402.

The spelling of 7128897891 in words is "seven billion, one hundred twenty-eight million, eight hundred ninety-seven thousand, eight hundred ninety-one".