128663391 has 8 divisors (see below), whose sum is σ = 171677440. Its totient is φ = 85712472.

The previous prime is 128663389. The next prime is 128663399. The reversal of 128663391 is 193366821.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 128663391 - 2¹ = 128663389 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 (128663399) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10801 + ... + 19338.

It is an arithmetic number, because the mean of its divisors is an integer number (21459680).

Almost surely, 2^128663391 is an apocalyptic number.

128663391 is a deficient number, since it is larger than the sum of its proper divisors (43014049).

128663391 is a wasteful number, since it uses less digits than its factorization.

128663391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31565.

The product of its digits is 46656, while the sum is 39.

The square root of 128663391 is about 11342.9886273416. The cubic root of 128663391 is about 504.8375662928.

The spelling of 128663391 in words is "one hundred twenty-eight million, six hundred sixty-three thousand, three hundred ninety-one".