209109091 has 2 divisors, whose sum is σ = 209109092. Its totient is φ = 209109090.

The previous prime is 209109071. The next prime is 209109097. The reversal of 209109091 is 190901902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 209109091 - 2⁹ = 209108579 is a prime.

It is a super-2 number, since 2×209109091² = 87453223877692562, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (209109097) 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, 104554545 + 104554546.

It is an arithmetic number, because the mean of its divisors is an integer number (104554546).

Almost surely, 2^209109091 is an apocalyptic number.

209109091 is a deficient number, since it is larger than the sum of its proper divisors (1).

209109091 is an equidigital number, since it uses as much as digits as its factorization.

209109091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1458, while the sum is 31.

The square root of 209109091 is about 14460.6047937145. The cubic root of 209109091 is about 593.5504492701.

The spelling of 209109091 in words is "two hundred nine million, one hundred nine thousand, ninety-one".