409891 has 2 divisors, whose sum is σ = 409892. Its totient is φ = 409890.

The previous prime is 409889. The next prime is 409897. The reversal of 409891 is 198904.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 409891 - 2¹ = 409889 is a prime.

Together with 409889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (409897) 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, 204945 + 204946.

It is an arithmetic number, because the mean of its divisors is an integer number (204946).

2⁴⁰⁹⁸⁹¹ is an apocalyptic number.

409891 is a deficient number, since it is larger than the sum of its proper divisors (1).

409891 is an equidigital number, since it uses as much as digits as its factorization.

409891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 409891 is about 640.2273033853. The cubic root of 409891 is about 74.2830044447.

The spelling of 409891 in words is "four hundred nine thousand, eight hundred ninety-one".