1221330221 has 4 divisors (see below), whose sum is σ = 1222175712. Its totient is φ = 1220484732.

The previous prime is 1221330217. The next prime is 1221330259. The reversal of 1221330221 is 1220331221.

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.

It is a cyclic number.

It is not a de Polignac number, because 1221330221 - 2² = 1221330217 is a prime.

It is a Duffinian number.

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 1221330221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221330211) 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, 420575 + ... + 423468.

It is an arithmetic number, because the mean of its divisors is an integer number (305543928).

Almost surely, 2^1221330221 is an apocalyptic number.

It is an amenable number.

1221330221 is a deficient number, since it is larger than the sum of its proper divisors (845491).

1221330221 is an equidigital number, since it uses as much as digits as its factorization.

1221330221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 845490.

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

The square root of 1221330221 is about 34947.5352635919. The cubic root of 1221330221 is about 1068.9179444659.

Adding to 1221330221 its reverse (1220331221), we get a palindrome (2441661442).

The spelling of 1221330221 in words is "one billion, two hundred twenty-one million, three hundred thirty thousand, two hundred twenty-one".