11161991 has 2 divisors, whose sum is σ = 11161992. Its totient is φ = 11161990.

The previous prime is 11161967. The next prime is 11161993. The reversal of 11161991 is 19916111.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 11161991 - 2¹⁰ = 11160967 is a prime.

Together with 11161993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11161993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5580995 + 5580996.

It is an arithmetic number, because the mean of its divisors is an integer number (5580996).

Almost surely, 2^11161991 is an apocalyptic number.

11161991 is a deficient number, since it is larger than the sum of its proper divisors (1).

11161991 is an equidigital number, since it uses as much as digits as its factorization.

11161991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 486, while the sum is 29.

The square root of 11161991 is about 3340.9565995385. The cubic root of 11161991 is about 223.4844048529.

The spelling of 11161991 in words is "eleven million, one hundred sixty-one thousand, nine hundred ninety-one".