9871891 has 2 divisors, whose sum is σ = 9871892. Its totient is φ = 9871890.

The previous prime is 9871877. The next prime is 9871907. The reversal of 9871891 is 1981789.

9871891 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 9871891 - 2²³ = 1483283 is a prime.

It is not a weakly prime, because it can be changed into another prime (9871291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4935945 + 4935946.

It is an arithmetic number, because the mean of its divisors is an integer number (4935946).

Almost surely, 2^9871891 is an apocalyptic number.

9871891 is a deficient number, since it is larger than the sum of its proper divisors (1).

9871891 is an equidigital number, since it uses as much as digits as its factorization.

9871891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36288, while the sum is 43.

The square root of 9871891 is about 3141.9565560332. The cubic root of 9871891 is about 214.5195038439.

The spelling of 9871891 in words is "nine million, eight hundred seventy-one thousand, eight hundred ninety-one".