21242191 has 2 divisors, whose sum is σ = 21242192. Its totient is φ = 21242190.

The previous prime is 21242153. The next prime is 21242201. The reversal of 21242191 is 19124212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21242191 - 2⁷ = 21242063 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21242101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10621095 + 10621096.

It is an arithmetic number, because the mean of its divisors is an integer number (10621096).

Almost surely, 2^21242191 is an apocalyptic number.

21242191 is a deficient number, since it is larger than the sum of its proper divisors (1).

21242191 is an equidigital number, since it uses as much as digits as its factorization.

21242191 is an evil number, because the sum of its binary digits is even.

The product of its digits is 288, while the sum is 22.

The square root of 21242191 is about 4608.9251458447. The cubic root of 21242191 is about 276.9489799033.

The spelling of 21242191 in words is "twenty-one million, two hundred forty-two thousand, one hundred ninety-one".