128116391 has 4 divisors (see below), whose sum is σ = 137971512. Its totient is φ = 118261272.

The previous prime is 128116381. The next prime is 128116421. The reversal of 128116391 is 193611821.

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 128116391 - 2¹⁰ = 128115367 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128116381) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4927541 + ... + 4927566.

It is an arithmetic number, because the mean of its divisors is an integer number (34492878).

Almost surely, 2^128116391 is an apocalyptic number.

128116391 is a deficient number, since it is larger than the sum of its proper divisors (9855121).

128116391 is an equidigital number, since it uses as much as digits as its factorization.

128116391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9855120.

The product of its digits is 2592, while the sum is 32.

The square root of 128116391 is about 11318.8511342804. The cubic root of 128116391 is about 504.1211272970.

The spelling of 128116391 in words is "one hundred twenty-eight million, one hundred sixteen thousand, three hundred ninety-one".