21011121191 has 4 divisors (see below), whose sum is σ = 21031501584. Its totient is φ = 20990740800.

The previous prime is 21011121179. The next prime is 21011121227. The reversal of 21011121191 is 19112111012.

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 21011121191 - 2⁶ = 21011121127 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 (21011421191) 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, 10188650 + ... + 10190711.

It is an arithmetic number, because the mean of its divisors is an integer number (5257875396).

Almost surely, 2^21011121191 is an apocalyptic number.

21011121191 is a deficient number, since it is larger than the sum of its proper divisors (20380393).

21011121191 is a wasteful number, since it uses less digits than its factorization.

21011121191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20380392.

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

The spelling of 21011121191 in words is "twenty-one billion, eleven million, one hundred twenty-one thousand, one hundred ninety-one".