391192421909 has 2 divisors, whose sum is σ = 391192421910. Its totient is φ = 391192421908.

The previous prime is 391192421863. The next prime is 391192421923. The reversal of 391192421909 is 909124291193.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 255899398225 + 135293023684 = 505865^2 + 367822^2 .

It is a cyclic number.

It is not a de Polignac number, because 391192421909 - 2²⁰ = 391191373333 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (391192421959) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195596210954 + 195596210955.

It is an arithmetic number, because the mean of its divisors is an integer number (195596210955).

Almost surely, 2^391192421909 is an apocalyptic number.

It is an amenable number.

391192421909 is a deficient number, since it is larger than the sum of its proper divisors (1).

391192421909 is an equidigital number, since it uses as much as digits as its factorization.

391192421909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 314928, while the sum is 50.

The spelling of 391192421909 in words is "three hundred ninety-one billion, one hundred ninety-two million, four hundred twenty-one thousand, nine hundred nine".