391921339 has 2 divisors, whose sum is σ = 391921340. Its totient is φ = 391921338.

The previous prime is 391921333. The next prime is 391921351. The reversal of 391921339 is 933129193.

It is a weak prime.

It is an emirp because it is prime and its reverse (933129193) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 391921339 - 2³ = 391921331 is a prime.

It is not a weakly prime, because it can be changed into another prime (391921331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195960669 + 195960670.

It is an arithmetic number, because the mean of its divisors is an integer number (195960670).

Almost surely, 2^391921339 is an apocalyptic number.

391921339 is a deficient number, since it is larger than the sum of its proper divisors (1).

391921339 is an equidigital number, since it uses as much as digits as its factorization.

391921339 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 39366, while the sum is 40.

The square root of 391921339 is about 19797.0032833255. The cubic root of 391921339 is about 731.8121855587.

The spelling of 391921339 in words is "three hundred ninety-one million, nine hundred twenty-one thousand, three hundred thirty-nine".