391321 has 4 divisors (see below), whose sum is σ = 447232. Its totient is φ = 335412.

The previous prime is 391301. The next prime is 391331. The reversal of 391321 is 123193.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 123193 = 7 ⋅17599.

It is not a de Polignac number, because 391321 - 2⁹ = 390809 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391301) 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 in 3 ways as a sum of consecutive naturals, for example, 27945 + ... + 27958.

It is an arithmetic number, because the mean of its divisors is an integer number (111808).

2³⁹¹³²¹ is an apocalyptic number.

It is an amenable number.

391321 is a deficient number, since it is larger than the sum of its proper divisors (55911).

391321 is an equidigital number, since it uses as much as digits as its factorization.

391321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55910.

The product of its digits is 162, while the sum is 19.

The square root of 391321 is about 625.5565521997. The cubic root of 391321 is about 73.1438335107.

The spelling of 391321 in words is "three hundred ninety-one thousand, three hundred twenty-one".