128858221 has 4 divisors (see below), whose sum is σ = 129679132. Its totient is φ = 128037312.

The previous prime is 128858207. The next prime is 128858231. The reversal of 128858221 is 122858821.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 35832196 + 93026025 = 5986^2 + 9645^2 .

It is a cyclic number.

It is not a de Polignac number, because 128858221 - 2⁵ = 128858189 is a prime.

It is a super-2 number, since 2×128858221² = 33208882238569682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128858231) 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, 410220 + ... + 410533.

It is an arithmetic number, because the mean of its divisors is an integer number (32419783).

Almost surely, 2^128858221 is an apocalyptic number.

It is an amenable number.

128858221 is a deficient number, since it is larger than the sum of its proper divisors (820911).

128858221 is an equidigital number, since it uses as much as digits as its factorization.

128858221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 820910.

The product of its digits is 20480, while the sum is 37.

The square root of 128858221 is about 11351.5735032638. The cubic root of 128858221 is about 505.0922564515.

The spelling of 128858221 in words is "one hundred twenty-eight million, eight hundred fifty-eight thousand, two hundred twenty-one".