391873 has 2 divisors, whose sum is σ = 391874. Its totient is φ = 391872.

The previous prime is 391861. The next prime is 391879. The reversal of 391873 is 378193.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 339889 + 51984 = 583^2 + 228^2 .

It is an emirp because it is prime and its reverse (378193) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 391873 - 2¹³ = 383681 is a prime.

391873 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (391879) 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, 195936 + 195937.

It is an arithmetic number, because the mean of its divisors is an integer number (195937).

2³⁹¹⁸⁷³ is an apocalyptic number.

It is an amenable number.

391873 is a deficient number, since it is larger than the sum of its proper divisors (1).

391873 is an equidigital number, since it uses as much as digits as its factorization.

391873 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4536, while the sum is 31.

The square root of 391873 is about 625.9976038293. The cubic root of 391873 is about 73.1782097443.

The spelling of 391873 in words is "three hundred ninety-one thousand, eight hundred seventy-three".