1331312221 has 2 divisors, whose sum is σ = 1331312222. Its totient is φ = 1331312220.

The previous prime is 1331312201. The next prime is 1331312237. The reversal of 1331312221 is 1222131331.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1323940996 + 7371225 = 36386^2 + 2715^2 .

It is an emirp because it is prime and its reverse (1222131331) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1331312221 - 2⁷ = 1331312093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1331312201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 665656110 + 665656111.

It is an arithmetic number, because the mean of its divisors is an integer number (665656111).

Almost surely, 2^1331312221 is an apocalyptic number.

It is an amenable number.

1331312221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1331312221 is an equidigital number, since it uses as much as digits as its factorization.

1331312221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 216, while the sum is 19.

The square root of 1331312221 is about 36487.1514508875. The cubic root of 1331312221 is about 1100.0860045702.

Adding to 1331312221 its reverse (1222131331), we get a palindrome (2553443552).

The spelling of 1331312221 in words is "one billion, three hundred thirty-one million, three hundred twelve thousand, two hundred twenty-one".