9981891 has 12 divisors (see below), whose sum is σ = 14754168. Its totient is φ = 6499584.

The previous prime is 9981889. The next prime is 9981899. The reversal of 9981891 is 1981899.

9981891 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 9981891 - 2¹ = 9981889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (9981899) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12510 + ... + 13283.

It is an arithmetic number, because the mean of its divisors is an integer number (1229514).

Almost surely, 2^9981891 is an apocalyptic number.

9981891 is a deficient number, since it is larger than the sum of its proper divisors (4772277).

9981891 is a wasteful number, since it uses less digits than its factorization.

9981891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25842 (or 25839 counting only the distinct ones).

The product of its digits is 46656, while the sum is 45.

The square root of 9981891 is about 3159.4130784055. The cubic root of 9981891 is about 215.3133415629.

The spelling of 9981891 in words is "nine million, nine hundred eighty-one thousand, eight hundred ninety-one".