33231221 has 2 divisors, whose sum is σ = 33231222. Its totient is φ = 33231220.

The previous prime is 33231179. The next prime is 33231223. The reversal of 33231221 is 12213233.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19018321 + 14212900 = 4361^2 + 3770^2 .

It is a cyclic number.

It is not a de Polignac number, because 33231221 - 2¹⁸ = 32969077 is a prime.

It is a super-2 number, since 2×33231221² = 2208628098301682, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 33231223, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 33231221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (33231223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16615610 + 16615611.

It is an arithmetic number, because the mean of its divisors is an integer number (16615611).

Almost surely, 2^33231221 is an apocalyptic number.

It is an amenable number.

33231221 is a deficient number, since it is larger than the sum of its proper divisors (1).

33231221 is an equidigital number, since it uses as much as digits as its factorization.

33231221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 216, while the sum is 17.

The square root of 33231221 is about 5764.6527215436. The cubic root of 33231221 is about 321.5008308137.

Adding to 33231221 its reverse (12213233), we get a palindrome (45444454).

The spelling of 33231221 in words is "thirty-three million, two hundred thirty-one thousand, two hundred twenty-one".