1211112191 has 4 divisors (see below), whose sum is σ = 1221830112. Its totient is φ = 1200394272.

The previous prime is 1211112163. The next prime is 1211112229. The reversal of 1211112191 is 1912111121.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1211112191 - 2¹⁴ = 1211095807 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 (1211112101) 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, 5358791 + ... + 5359016.

It is an arithmetic number, because the mean of its divisors is an integer number (305457528).

Almost surely, 2^1211112191 is an apocalyptic number.

1211112191 is a deficient number, since it is larger than the sum of its proper divisors (10717921).

1211112191 is a wasteful number, since it uses less digits than its factorization.

1211112191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10717920.

The product of its digits is 36, while the sum is 20.

The square root of 1211112191 is about 34801.0372115545. The cubic root of 1211112191 is about 1065.9286252749.

It can be divided in two parts, 12111121 and 91, that multiplied together give a palindrome (1102112011).

The spelling of 1211112191 in words is "one billion, two hundred eleven million, one hundred twelve thousand, one hundred ninety-one".