128912221 has 8 divisors (see below), whose sum is σ = 135349920. Its totient is φ = 122607408.

The previous prime is 128912213. The next prime is 128912243. The reversal of 128912221 is 122219821.

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

It is a cyclic number.

It is not a de Polignac number, because 128912221 - 2³ = 128912213 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 128912221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128912281) 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 7 ways as a sum of consecutive naturals, for example, 31231 + ... + 35116.

It is an arithmetic number, because the mean of its divisors is an integer number (16918740).

Almost surely, 2^128912221 is an apocalyptic number.

It is an amenable number.

128912221 is a deficient number, since it is larger than the sum of its proper divisors (6437699).

128912221 is an equidigital number, since it uses as much as digits as its factorization.

128912221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66443.

The product of its digits is 1152, while the sum is 28.

The square root of 128912221 is about 11353.9517790063. The cubic root of 128912221 is about 505.1628021322.

The spelling of 128912221 in words is "one hundred twenty-eight million, nine hundred twelve thousand, two hundred twenty-one".