191012209 has 2 divisors, whose sum is σ = 191012210. Its totient is φ = 191012208.

The previous prime is 191012201. The next prime is 191012219. The reversal of 191012209 is 902210191.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 187772209 + 3240000 = 13703^2 + 1800^2 .

It is a cyclic number.

It is not a de Polignac number, because 191012209 - 2³ = 191012201 is a prime.

It is not a weakly prime, because it can be changed into another prime (191012201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95506104 + 95506105.

It is an arithmetic number, because the mean of its divisors is an integer number (95506105).

Almost surely, 2^191012209 is an apocalyptic number.

It is an amenable number.

191012209 is a deficient number, since it is larger than the sum of its proper divisors (1).

191012209 is an equidigital number, since it uses as much as digits as its factorization.

191012209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 25.

The square root of 191012209 is about 13820.7166601447. The cubic root of 191012209 is about 575.9087925044.

The spelling of 191012209 in words is "one hundred ninety-one million, twelve thousand, two hundred nine".