21111930191 has 4 divisors (see below), whose sum is σ = 23031196584. Its totient is φ = 19192663800.

The previous prime is 21111930167. The next prime is 21111930193. The reversal of 21111930191 is 19103911112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21111930191 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111930193) 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, 959633180 + ... + 959633201.

It is an arithmetic number, because the mean of its divisors is an integer number (5757799146).

Almost surely, 2^21111930191 is an apocalyptic number.

21111930191 is a deficient number, since it is larger than the sum of its proper divisors (1919266393).

21111930191 is a wasteful number, since it uses less digits than its factorization.

21111930191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1919266392.

The product of its (nonzero) digits is 486, while the sum is 29.

The spelling of 21111930191 in words is "twenty-one billion, one hundred eleven million, nine hundred thirty thousand, one hundred ninety-one".