491857 has 2 divisors, whose sum is σ = 491858. Its totient is φ = 491856.

The previous prime is 491851. The next prime is 491867. The reversal of 491857 is 758194.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 450241 + 41616 = 671^2 + 204^2 .

It is a cyclic number.

It is not a de Polignac number, because 491857 - 2¹⁵ = 459089 is a prime.

It is not a weakly prime, because it can be changed into another prime (491851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 245928 + 245929.

It is an arithmetic number, because the mean of its divisors is an integer number (245929).

2⁴⁹¹⁸⁵⁷ is an apocalyptic number.

It is an amenable number.

491857 is a deficient number, since it is larger than the sum of its proper divisors (1).

491857 is an equidigital number, since it uses as much as digits as its factorization.

491857 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10080, while the sum is 34.

The square root of 491857 is about 701.3251742238. The cubic root of 491857 is about 78.9368185747.

The spelling of 491857 in words is "four hundred ninety-one thousand, eight hundred fifty-seven".