391399 has 2 divisors, whose sum is σ = 391400. Its totient is φ = 391398.

The previous prime is 391397. The next prime is 391403. The reversal of 391399 is 993193.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 391399 - 2¹ = 391397 is a prime.

Together with 391397, it forms a pair of twin primes.

It is an Ulam number.

391399 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (391393) 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, 195699 + 195700.

It is an arithmetic number, because the mean of its divisors is an integer number (195700).

2³⁹¹³⁹⁹ is an apocalyptic number.

391399 is a deficient number, since it is larger than the sum of its proper divisors (1).

391399 is an equidigital number, since it uses as much as digits as its factorization.

391399 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6561, while the sum is 34.

The square root of 391399 is about 625.6188935766. The cubic root of 391399 is about 73.1486929824.

The spelling of 391399 in words is "three hundred ninety-one thousand, three hundred ninety-nine".