211221091 has 2 divisors, whose sum is σ = 211221092. Its totient is φ = 211221090.

The previous prime is 211221077. The next prime is 211221169. The reversal of 211221091 is 190122112.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 211221091 - 2⁹ = 211220579 is a prime.

It is a super-2 number, since 2×211221091² = 89228698566460562, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (211221061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105610545 + 105610546.

It is an arithmetic number, because the mean of its divisors is an integer number (105610546).

Almost surely, 2^211221091 is an apocalyptic number.

211221091 is a deficient number, since it is larger than the sum of its proper divisors (1).

211221091 is an equidigital number, since it uses as much as digits as its factorization.

211221091 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 19.

The square root of 211221091 is about 14533.4473198894. The cubic root of 211221091 is about 595.5420440052.

The spelling of 211221091 in words is "two hundred eleven million, two hundred twenty-one thousand, ninety-one".