291191009 has 2 divisors, whose sum is σ = 291191010. Its totient is φ = 291191008.

The previous prime is 291190997. The next prime is 291191057. The reversal of 291191009 is 900191192.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 281299984 + 9891025 = 16772^2 + 3145^2 .

It is a cyclic number.

It is not a de Polignac number, because 291191009 - 2²⁸ = 22755553 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (291191309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 145595504 + 145595505.

It is an arithmetic number, because the mean of its divisors is an integer number (145595505).

Almost surely, 2^291191009 is an apocalyptic number.

It is an amenable number.

291191009 is a deficient number, since it is larger than the sum of its proper divisors (1).

291191009 is an equidigital number, since it uses as much as digits as its factorization.

291191009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1458, while the sum is 32.

The square root of 291191009 is about 17064.3197637644. The cubic root of 291191009 is about 662.8154967691.

The spelling of 291191009 in words is "two hundred ninety-one million, one hundred ninety-one thousand, nine".