21912211 has 2 divisors, whose sum is σ = 21912212. Its totient is φ = 21912210.

The previous prime is 21912193. The next prime is 21912217. The reversal of 21912211 is 11221912.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21912211 - 2⁵ = 21912179 is a prime.

It is not a weakly prime, because it can be changed into another prime (21912217) 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, 10956105 + 10956106.

It is an arithmetic number, because the mean of its divisors is an integer number (10956106).

Almost surely, 2^21912211 is an apocalyptic number.

21912211 is a deficient number, since it is larger than the sum of its proper divisors (1).

21912211 is an equidigital number, since it uses as much as digits as its factorization.

21912211 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72, while the sum is 19.

The square root of 21912211 is about 4681.0480664056. The cubic root of 21912211 is about 279.8307267686.

The spelling of 21912211 in words is "twenty-one million, nine hundred twelve thousand, two hundred eleven".