12131221 has 4 divisors (see below), whose sum is σ = 12312352. Its totient is φ = 11950092.

The previous prime is 12131219. The next prime is 12131257. The reversal of 12131221 is 12213121.

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: 12213121 = 41 ⋅297881.

It is a cyclic number.

It is not a de Polignac number, because 12131221 - 2¹ = 12131219 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12131321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 90465 + ... + 90598.

It is an arithmetic number, because the mean of its divisors is an integer number (3078088).

Almost surely, 2^12131221 is an apocalyptic number.

It is an amenable number.

12131221 is a deficient number, since it is larger than the sum of its proper divisors (181131).

12131221 is an equidigital number, since it uses as much as digits as its factorization.

12131221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 181130.

The product of its digits is 24, while the sum is 13.

The square root of 12131221 is about 3482.9902382866. The cubic root of 12131221 is about 229.7743281116.

Adding to 12131221 its reverse (12213121), we get a palindrome (24344342).

The spelling of 12131221 in words is "twelve million, one hundred thirty-one thousand, two hundred twenty-one".