391331 has 2 divisors, whose sum is σ = 391332. Its totient is φ = 391330.

The previous prime is 391301. The next prime is 391337. The reversal of 391331 is 133193.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 391331 - 2¹⁰ = 390307 is a prime.

It is a super-2 number, since 2×391331² = 306279903122, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (391337) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195665 + 195666.

It is an arithmetic number, because the mean of its divisors is an integer number (195666).

2³⁹¹³³¹ is an apocalyptic number.

391331 is a deficient number, since it is larger than the sum of its proper divisors (1).

391331 is an equidigital number, since it uses as much as digits as its factorization.

391331 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 243, while the sum is 20.

The square root of 391331 is about 625.5645450311. The cubic root of 391331 is about 73.1444565560.

The spelling of 391331 in words is "three hundred ninety-one thousand, three hundred thirty-one".