128491 has 4 divisors (see below), whose sum is σ = 140184. Its totient is φ = 116800.

The previous prime is 128489. The next prime is 128509. The reversal of 128491 is 194821.

It is a happy number.

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 128491 - 2¹ = 128489 is a prime.

128491 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (128411) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5830 + ... + 5851.

It is an arithmetic number, because the mean of its divisors is an integer number (35046).

2¹²⁸⁴⁹¹ is an apocalyptic number.

128491 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

128491 is a deficient number, since it is larger than the sum of its proper divisors (11693).

128491 is a wasteful number, since it uses less digits than its factorization.

128491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11692.

The product of its digits is 576, while the sum is 25.

The square root of 128491 is about 358.4564129709. The cubic root of 128491 is about 50.4611994874.

The spelling of 128491 in words is "one hundred twenty-eight thousand, four hundred ninety-one".