1331221121 has 2 divisors, whose sum is σ = 1331221122. Its totient is φ = 1331221120.

The previous prime is 1331221109. The next prime is 1331221231. The reversal of 1331221121 is 1211221331.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 998560000 + 332661121 = 31600^2 + 18239^2 .

It is a cyclic number.

It is not a de Polignac number, because 1331221121 - 2¹⁸ = 1330958977 is a prime.

It is a Sophie Germain prime.

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 1331221121.

It is not a weakly prime, because it can be changed into another prime (1331221321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 665610560 + 665610561.

It is an arithmetic number, because the mean of its divisors is an integer number (665610561).

Almost surely, 2^1331221121 is an apocalyptic number.

It is an amenable number.

1331221121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1331221121 is an equidigital number, since it uses as much as digits as its factorization.

1331221121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72, while the sum is 17.

The square root of 1331221121 is about 36485.9030448747. The cubic root of 1331221121 is about 1100.0609115031.

Adding to 1331221121 its reverse (1211221331), we get a palindrome (2542442452).

The spelling of 1331221121 in words is "one billion, three hundred thirty-one million, two hundred twenty-one thousand, one hundred twenty-one".