128778261 has 8 divisors (see below), whose sum is σ = 175357824. Its totient is φ = 84025440.

The previous prime is 128778227. The next prime is 128778271. The reversal of 128778261 is 162877821.

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

It is not a de Polignac number, because 128778261 - 2⁶ = 128778197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128778271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 456520 + ... + 456801.

It is an arithmetic number, because the mean of its divisors is an integer number (21919728).

Almost surely, 2^128778261 is an apocalyptic number.

It is an amenable number.

128778261 is a deficient number, since it is larger than the sum of its proper divisors (46579563).

128778261 is an equidigital number, since it uses as much as digits as its factorization.

128778261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 913371.

The product of its digits is 75264, while the sum is 42.

The square root of 128778261 is about 11348.0509780314. The cubic root of 128778261 is about 504.9877603804.

The spelling of 128778261 in words is "one hundred twenty-eight million, seven hundred seventy-eight thousand, two hundred sixty-one".