391917 has 4 divisors (see below), whose sum is σ = 522560. Its totient is φ = 261276.

The previous prime is 391907. The next prime is 391921. The reversal of 391917 is 719193.

391917 is an esthetic number in base 9, because in such base its adjacent digits differ by 1.

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: 719193 = 3 ⋅239731.

It is not a de Polignac number, because 391917 - 2⁷ = 391789 is a prime.

It is a D-number.

It is a Duffinian number.

It is a plaindrome in base 6.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 391917.

It is not an unprimeable number, because it can be changed into a prime (391907) by changing a digit.

It is an upside-down number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65317 + ... + 65322.

It is an arithmetic number, because the mean of its divisors is an integer number (130640).

2³⁹¹⁹¹⁷ is an apocalyptic number.

It is an amenable number.

391917 is a deficient number, since it is larger than the sum of its proper divisors (130643).

391917 is a wasteful number, since it uses less digits than its factorization.

391917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130642.

The product of its digits is 1701, while the sum is 30.

The square root of 391917 is about 626.0327467473. The cubic root of 391917 is about 73.1809484894.

The spelling of 391917 in words is "three hundred ninety-one thousand, nine hundred seventeen".