1211221091 has 2 divisors, whose sum is σ = 1211221092. Its totient is φ = 1211221090.

The previous prime is 1211221087. The next prime is 1211221093. The reversal of 1211221091 is 1901221121.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1211221091 - 2² = 1211221087 is a prime.

Together with 1211221093, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1211221093) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605610545 + 605610546.

It is an arithmetic number, because the mean of its divisors is an integer number (605610546).

Almost surely, 2^1211221091 is an apocalyptic number.

1211221091 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211221091 is an equidigital number, since it uses as much as digits as its factorization.

1211221091 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 20.

The square root of 1211221091 is about 34802.6017849241. The cubic root of 1211221091 is about 1065.9605728102.

The spelling of 1211221091 in words is "one billion, two hundred eleven million, two hundred twenty-one thousand, ninety-one".