33128221 has 4 divisors (see below), whose sum is σ = 37860832. Its totient is φ = 28395612.

The previous prime is 33128201. The next prime is 33128273. The reversal of 33128221 is 12282133.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12282133 = 43 ⋅285631.

It is not a de Polignac number, because 33128221 - 2⁷ = 33128093 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 33128192 and 33128201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (33128201) 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, 2366295 + ... + 2366308.

It is an arithmetic number, because the mean of its divisors is an integer number (9465208).

Almost surely, 2^33128221 is an apocalyptic number.

It is an amenable number.

33128221 is a deficient number, since it is larger than the sum of its proper divisors (4732611).

33128221 is an equidigital number, since it uses as much as digits as its factorization.

33128221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4732610.

The product of its digits is 576, while the sum is 22.

The square root of 33128221 is about 5755.7120324075. The cubic root of 33128221 is about 321.1683236469.

The spelling of 33128221 in words is "thirty-three million, one hundred twenty-eight thousand, two hundred twenty-one".