391091 has 4 divisors (see below), whose sum is σ = 394992. Its totient is φ = 387192.

The previous prime is 391073. The next prime is 391103. The reversal of 391091 is 190193.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 190193 = 89 ⋅2137.

It is a cyclic number.

It is not a de Polignac number, because 391091 - 2¹⁰ = 390067 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (391021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1796 + ... + 2001.

It is an arithmetic number, because the mean of its divisors is an integer number (98748).

2³⁹¹⁰⁹¹ is an apocalyptic number.

391091 is a deficient number, since it is larger than the sum of its proper divisors (3901).

391091 is a wasteful number, since it uses less digits than its factorization.

391091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3900.

The product of its (nonzero) digits is 243, while the sum is 23.

The square root of 391091 is about 625.3726888824. The cubic root of 391091 is about 73.1295005387.

The spelling of 391091 in words is "three hundred ninety-one thousand, ninety-one".