21121111191 has 32 divisors (see below), whose sum is σ = 29958543360. Its totient is φ = 13210694784.

The previous prime is 21121111153. The next prime is 21121111279. The reversal of 21121111191 is 19111112112.

It is a happy number.

It is not a de Polignac number, because 21121111191 - 2⁶ = 21121111127 is a prime.

It is a super-2 number, since 2×21121111191² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121311191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2774196 + ... + 2781798.

It is an arithmetic number, because the mean of its divisors is an integer number (936204480).

Almost surely, 2^21121111191 is an apocalyptic number.

21121111191 is a deficient number, since it is larger than the sum of its proper divisors (8837432169).

21121111191 is a wasteful number, since it uses less digits than its factorization.

21121111191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8535.

The product of its digits is 36, while the sum is 21.

The spelling of 21121111191 in words is "twenty-one billion, one hundred twenty-one million, one hundred eleven thousand, one hundred ninety-one".