21121010191 has 4 divisors (see below), whose sum is σ = 21129996384. Its totient is φ = 21112024000.

The previous prime is 21121010167. The next prime is 21121010221. The reversal of 21121010191 is 19101012112.

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 21121010191 - 2⁷ = 21121010063 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 (21121010591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4489570 + ... + 4494271.

It is an arithmetic number, because the mean of its divisors is an integer number (5282499096).

Almost surely, 2^21121010191 is an apocalyptic number.

21121010191 is a deficient number, since it is larger than the sum of its proper divisors (8986193).

21121010191 is an equidigital number, since it uses as much as digits as its factorization.

21121010191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8986192.

The product of its (nonzero) digits is 36, while the sum is 19.

The spelling of 21121010191 in words is "twenty-one billion, one hundred twenty-one million, ten thousand, one hundred ninety-one".