21211020191 has 2 divisors, whose sum is σ = 21211020192. Its totient is φ = 21211020190.

The previous prime is 21211020163. The next prime is 21211020269. The reversal of 21211020191 is 19102011212.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21211020191 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21211023191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605510095 + 10605510096.

It is an arithmetic number, because the mean of its divisors is an integer number (10605510096).

Almost surely, 2^21211020191 is an apocalyptic number.

21211020191 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211020191 is an equidigital number, since it uses as much as digits as its factorization.

21211020191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 20.

The spelling of 21211020191 in words is "twenty-one billion, two hundred eleven million, twenty thousand, one hundred ninety-one".