671959891 has 2 divisors, whose sum is σ = 671959892. Its totient is φ = 671959890.

The previous prime is 671959889. The next prime is 671959907. The reversal of 671959891 is 198959176.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 671959891 - 2¹ = 671959889 is a prime.

It is a super-2 number, since 2×671959891² = 903060190225463762, which contains 22 as substring.

Together with 671959889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (671959861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 335979945 + 335979946.

It is an arithmetic number, because the mean of its divisors is an integer number (335979946).

Almost surely, 2^671959891 is an apocalyptic number.

671959891 is a deficient number, since it is larger than the sum of its proper divisors (1).

671959891 is an equidigital number, since it uses as much as digits as its factorization.

671959891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1224720, while the sum is 55.

The square root of 671959891 is about 25922.1891629546. The cubic root of 671959891 is about 875.8864012288.

The spelling of 671959891 in words is "six hundred seventy-one million, nine hundred fifty-nine thousand, eight hundred ninety-one".