21011191 has 2 divisors, whose sum is σ = 21011192. Its totient is φ = 21011190.

The previous prime is 21011183. The next prime is 21011231. The reversal of 21011191 is 19111012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21011191 - 2³ = 21011183 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21011141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505595 + 10505596.

It is an arithmetic number, because the mean of its divisors is an integer number (10505596).

Almost surely, 2^21011191 is an apocalyptic number.

21011191 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011191 is an equidigital number, since it uses as much as digits as its factorization.

21011191 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18, while the sum is 16.

The square root of 21011191 is about 4583.7965705297. The cubic root of 21011191 is about 275.9414170628.

The spelling of 21011191 in words is "twenty-one million, eleven thousand, one hundred ninety-one".