128778251 has 4 divisors (see below), whose sum is σ = 147175152. Its totient is φ = 110381352.

The previous prime is 128778227. The next prime is 128778271. The reversal of 128778251 is 152877821.

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 128778251 - 2⁶ = 128778187 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 128778199 and 128778208.

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 3 ways as a sum of consecutive naturals, for example, 9198440 + ... + 9198453.

It is an arithmetic number, because the mean of its divisors is an integer number (36793788).

Almost surely, 2^128778251 is an apocalyptic number.

128778251 is a deficient number, since it is larger than the sum of its proper divisors (18396901).

128778251 is an equidigital number, since it uses as much as digits as its factorization.

128778251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18396900.

The product of its digits is 62720, while the sum is 41.

The square root of 128778251 is about 11348.0505374271. The cubic root of 128778251 is about 504.9877473092.

The spelling of 128778251 in words is "one hundred twenty-eight million, seven hundred seventy-eight thousand, two hundred fifty-one".