1165311221 has 2 divisors, whose sum is σ = 1165311222. Its totient is φ = 1165311220.

The previous prime is 1165311193. The next prime is 1165311247. The reversal of 1165311221 is 1221135611.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 912946225 + 252364996 = 30215^2 + 15886^2 .

It is a cyclic number.

It is not a de Polignac number, because 1165311221 - 2⁶ = 1165311157 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1165311281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 582655610 + 582655611.

It is an arithmetic number, because the mean of its divisors is an integer number (582655611).

Almost surely, 2^1165311221 is an apocalyptic number.

It is an amenable number.

1165311221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1165311221 is an equidigital number, since it uses as much as digits as its factorization.

1165311221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 360, while the sum is 23.

The square root of 1165311221 is about 34136.6550939016. The cubic root of 1165311221 is about 1052.3187519906.

Adding to 1165311221 its reverse (1221135611), we get a palindrome (2386446832).

The spelling of 1165311221 in words is "one billion, one hundred sixty-five million, three hundred eleven thousand, two hundred twenty-one".