393900391 has 2 divisors, whose sum is σ = 393900392. Its totient is φ = 393900390.

The previous prime is 393900389. The next prime is 393900427. The reversal of 393900391 is 193009393.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 393900391 - 2¹ = 393900389 is a prime.

Together with 393900389, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 393900391.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (393900361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 196950195 + 196950196.

It is an arithmetic number, because the mean of its divisors is an integer number (196950196).

Almost surely, 2^393900391 is an apocalyptic number.

393900391 is a deficient number, since it is larger than the sum of its proper divisors (1).

393900391 is an equidigital number, since it uses as much as digits as its factorization.

393900391 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19683, while the sum is 37.

The square root of 393900391 is about 19846.9239682123. The cubic root of 393900391 is about 733.0419080097.

The spelling of 393900391 in words is "three hundred ninety-three million, nine hundred thousand, three hundred ninety-one".