11115991 has 4 divisors (see below), whose sum is σ = 11134912. Its totient is φ = 11097072.

The previous prime is 11115989. The next prime is 11115997. The reversal of 11115991 is 19951111.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19951111 = 1489 ⋅13399.

It is a cyclic number.

It is not a de Polignac number, because 11115991 - 2¹ = 11115989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11115997) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8550 + ... + 9763.

It is an arithmetic number, because the mean of its divisors is an integer number (2783728).

Almost surely, 2^11115991 is an apocalyptic number.

11115991 is a deficient number, since it is larger than the sum of its proper divisors (18921).

11115991 is an equidigital number, since it uses as much as digits as its factorization.

11115991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18920.

The product of its digits is 405, while the sum is 28.

The square root of 11115991 is about 3334.0652363144. The cubic root of 11115991 is about 223.1769794969.

The spelling of 11115991 in words is "eleven million, one hundred fifteen thousand, nine hundred ninety-one".