21224191 has 2 divisors, whose sum is σ = 21224192. Its totient is φ = 21224190.

The previous prime is 21224173. The next prime is 21224207. The reversal of 21224191 is 19142212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21224191 - 2¹¹ = 21222143 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21224131) 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 as a sum of consecutive naturals, namely, 10612095 + 10612096.

It is an arithmetic number, because the mean of its divisors is an integer number (10612096).

Almost surely, 2^21224191 is an apocalyptic number.

21224191 is a deficient number, since it is larger than the sum of its proper divisors (1).

21224191 is an equidigital number, since it uses as much as digits as its factorization.

21224191 is an odious number, because the sum of its binary digits is odd.

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

The square root of 21224191 is about 4606.9719990467. The cubic root of 21224191 is about 276.8707316916.

The spelling of 21224191 in words is "twenty-one million, two hundred twenty-four thousand, one hundred ninety-one".