128128249 has 4 divisors (see below), whose sum is σ = 128158564. Its totient is φ = 128097936.

The previous prime is 128128241. The next prime is 128128279. The reversal of 128128249 is 942821821.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 942821821 = 691 ⋅1364431.

It can be written as a sum of positive squares in 2 ways, for example, as 114490000 + 13638249 = 10700^2 + 3693^2 .

It is a cyclic number.

It is not a de Polignac number, because 128128249 - 2³ = 128128241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128128241) 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, 7542 + ... + 17695.

It is an arithmetic number, because the mean of its divisors is an integer number (32039641).

Almost surely, 2^128128249 is an apocalyptic number.

It is an amenable number.

128128249 is a deficient number, since it is larger than the sum of its proper divisors (30315).

128128249 is an equidigital number, since it uses as much as digits as its factorization.

128128249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30314.

The product of its digits is 18432, while the sum is 37.

The square root of 128128249 is about 11319.3749385732. The cubic root of 128128249 is about 504.1366800400.

The spelling of 128128249 in words is "one hundred twenty-eight million, one hundred twenty-eight thousand, two hundred forty-nine".