391217 has 2 divisors, whose sum is σ = 391218. Its totient is φ = 391216.

The previous prime is 391199. The next prime is 391219. The reversal of 391217 is 712193.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 303601 + 87616 = 551^2 + 296^2 .

It is a cyclic number.

It is not a de Polignac number, because 391217 - 2⁸ = 390961 is a prime.

Together with 391219, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 391192 and 391201.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 391217.

It is not a weakly prime, because it can be changed into another prime (391219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195608 + 195609.

It is an arithmetic number, because the mean of its divisors is an integer number (195609).

2³⁹¹²¹⁷ is an apocalyptic number.

It is an amenable number.

391217 is a deficient number, since it is larger than the sum of its proper divisors (1).

391217 is an equidigital number, since it uses as much as digits as its factorization.

391217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 378, while the sum is 23.

The square root of 391217 is about 625.4734206983. The cubic root of 391217 is about 73.1373532105.

The spelling of 391217 in words is "three hundred ninety-one thousand, two hundred seventeen".