491651 has 2 divisors, whose sum is σ = 491652. Its totient is φ = 491650.

The previous prime is 491639. The next prime is 491653. The reversal of 491651 is 156194.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 491651 - 2¹⁰ = 490627 is a prime.

Together with 491653, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p₄₀₈₉₅ and since 491651 and 40895 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 491651.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 491651.

It is not a weakly prime, because it can be changed into another prime (491653) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 245825 + 245826.

It is an arithmetic number, because the mean of its divisors is an integer number (245826).

2⁴⁹¹⁶⁵¹ is an apocalyptic number.

491651 is a deficient number, since it is larger than the sum of its proper divisors (1).

491651 is an equidigital number, since it uses as much as digits as its factorization.

491651 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1080, while the sum is 26.

The square root of 491651 is about 701.1782940166. The cubic root of 491651 is about 78.9257969056.

The spelling of 491651 in words is "four hundred ninety-one thousand, six hundred fifty-one".