1216322509 has 2 divisors, whose sum is σ = 1216322510. Its totient is φ = 1216322508.

The previous prime is 1216322377. The next prime is 1216322531. The reversal of 1216322509 is 9052236121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1208605225 + 7717284 = 34765^2 + 2778^2 .

It is a cyclic number.

It is not a de Polignac number, because 1216322509 - 2¹¹ = 1216320461 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1216322539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 608161254 + 608161255.

It is an arithmetic number, because the mean of its divisors is an integer number (608161255).

Almost surely, 2^1216322509 is an apocalyptic number.

It is an amenable number.

1216322509 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216322509 is an equidigital number, since it uses as much as digits as its factorization.

1216322509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 1216322509 is about 34875.8155316833. The cubic root of 1216322509 is about 1067.4550133788.

The spelling of 1216322509 in words is "one billion, two hundred sixteen million, three hundred twenty-two thousand, five hundred nine".