11156991 has 4 divisors (see below), whose sum is σ = 14875992. Its totient is φ = 7437992.

The previous prime is 11156989. The next prime is 11157053. The reversal of 11156991 is 19965111.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19965111 = 3 ⋅6655037.

It is a cyclic number.

It is not a de Polignac number, because 11156991 - 2¹ = 11156989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11156941) 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 in 3 ways as a sum of consecutive naturals, for example, 1859496 + ... + 1859501.

It is an arithmetic number, because the mean of its divisors is an integer number (3718998).

Almost surely, 2^11156991 is an apocalyptic number.

11156991 is a deficient number, since it is larger than the sum of its proper divisors (3719001).

11156991 is an equidigital number, since it uses as much as digits as its factorization.

11156991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3719000.

The product of its digits is 2430, while the sum is 33.

The square root of 11156991 is about 3340.2082270421. The cubic root of 11156991 is about 223.4510300151.

The spelling of 11156991 in words is "eleven million, one hundred fifty-six thousand, nine hundred ninety-one".