11997911509 has 2 divisors, whose sum is σ = 11997911510. Its totient is φ = 11997911508.

The previous prime is 11997911413. The next prime is 11997911531. The reversal of 11997911509 is 90511979911.

11997911509 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10385648100 + 1612263409 = 101910^2 + 40153^2 .

It is an emirp because it is prime and its reverse (90511979911) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 11997911509 - 2¹⁷ = 11997780437 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11997911309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5998955754 + 5998955755.

It is an arithmetic number, because the mean of its divisors is an integer number (5998955755).

Almost surely, 2^11997911509 is an apocalyptic number.

It is an amenable number.

11997911509 is a deficient number, since it is larger than the sum of its proper divisors (1).

11997911509 is an equidigital number, since it uses as much as digits as its factorization.

11997911509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 229635, while the sum is 52.

The spelling of 11997911509 in words is "eleven billion, nine hundred ninety-seven million, nine hundred eleven thousand, five hundred nine".