128897491 has 4 divisors (see below), whose sum is σ = 128961000. Its totient is φ = 128833984.

The previous prime is 128897479. The next prime is 128897533. The reversal of 128897491 is 194798821.

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 128897491 - 2⁹ = 128896979 is a prime.

It is a super-2 number, since 2×128897491² = 33229126372190162, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128897401) 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, 28606 + ... + 32803.

It is an arithmetic number, because the mean of its divisors is an integer number (32240250).

Almost surely, 2^128897491 is an apocalyptic number.

128897491 is a deficient number, since it is larger than the sum of its proper divisors (63509).

128897491 is an equidigital number, since it uses as much as digits as its factorization.

128897491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63508.

The product of its digits is 290304, while the sum is 49.

The square root of 128897491 is about 11353.3030876481. The cubic root of 128897491 is about 505.1435607925.

The spelling of 128897491 in words is "one hundred twenty-eight million, eight hundred ninety-seven thousand, four hundred ninety-one".