11199991 has 16 divisors (see below), whose sum is σ = 13087008. Its totient is φ = 9472000.

The previous prime is 11199989. The next prime is 11200001. The reversal of 11199991 is 19999111.

It is a cyclic number.

It is not a de Polignac number, because 11199991 - 2¹ = 11199989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11199901) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18591 + ... + 19183.

It is an arithmetic number, because the mean of its divisors is an integer number (817938).

Almost surely, 2^11199991 is an apocalyptic number.

11199991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

11199991 is a deficient number, since it is larger than the sum of its proper divisors (1887017).

11199991 is a wasteful number, since it uses less digits than its factorization.

11199991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 722.

The product of its digits is 6561, while the sum is 40.

The square root of 11199991 is about 3346.6387615038. The cubic root of 11199991 is about 223.7377284865.

It can be divided in two parts, 11 and 199991, that added together give a palindrome (200002).

The spelling of 11199991 in words is "eleven million, one hundred ninety-nine thousand, nine hundred ninety-one".