1331221 has 4 divisors (see below), whose sum is σ = 1339552. Its totient is φ = 1322892.

The previous prime is 1331207. The next prime is 1331227. The reversal of 1331221 is 1221331.

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: 1221331 = 17 ⋅71843.

It is a cyclic number.

It is not a de Polignac number, because 1331221 - 2⁷ = 1331093 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1331227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3921 + ... + 4246.

It is an arithmetic number, because the mean of its divisors is an integer number (334888).

2^1331221 is an apocalyptic number.

It is an amenable number.

1331221 is a deficient number, since it is larger than the sum of its proper divisors (8331).

1331221 is an equidigital number, since it uses as much as digits as its factorization.

1331221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8330.

The product of its digits is 36, while the sum is 13.

The square root of 1331221 is about 1153.7855086627. The cubic root of 1331221 is about 110.0060878173.

Adding to 1331221 its reverse (1221331), we get a palindrome (2552552).

The spelling of 1331221 in words is "one million, three hundred thirty-one thousand, two hundred twenty-one".