331221221 has 16 divisors (see below), whose sum is σ = 348131520. Its totient is φ = 314870400.

The previous prime is 331221203. The next prime is 331221239. The reversal of 331221221 is 122122133.

It is an interprime number because it is at equal distance from previous prime (331221203) and next prime (331221239).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-331221221 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 331221221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (331221271) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 227546 + ... + 228996.

It is an arithmetic number, because the mean of its divisors is an integer number (21758220).

Almost surely, 2^331221221 is an apocalyptic number.

It is an amenable number.

331221221 is a deficient number, since it is larger than the sum of its proper divisors (16910299).

331221221 is a wasteful number, since it uses less digits than its factorization.

331221221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1636.

The product of its digits is 144, while the sum is 17.

The square root of 331221221 is about 18199.4840860943. The cubic root of 331221221 is about 691.8937134197.

Adding to 331221221 its reverse (122122133), we get a palindrome (453343354).

It can be divided in two parts, 33122 and 1221, that added together give a palindrome (34343).

The spelling of 331221221 in words is "three hundred thirty-one million, two hundred twenty-one thousand, two hundred twenty-one".