9871981 has 24 divisors (see below), whose sum is σ = 12155136. Its totient is φ = 7983360.

The previous prime is 9871973. The next prime is 9871993. The reversal of 9871981 is 1891789.

9871981 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 9871981 - 2³ = 9871973 is a prime.

It is a super-2 number, since 2×9871981² = 194912017728722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9871931) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 101725 + ... + 101821.

It is an arithmetic number, because the mean of its divisors is an integer number (506464).

Almost surely, 2^9871981 is an apocalyptic number.

It is an amenable number.

9871981 is a deficient number, since it is larger than the sum of its proper divisors (2283155).

9871981 is a wasteful number, since it uses less digits than its factorization.

9871981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 209 (or 202 counting only the distinct ones).

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

The square root of 9871981 is about 3141.9708782864. The cubic root of 9871981 is about 214.5201557520.

The spelling of 9871981 in words is "nine million, eight hundred seventy-one thousand, nine hundred eighty-one".