9811985 has 4 divisors (see below), whose sum is σ = 11774388. Its totient is φ = 7849584.

The previous prime is 9811981. The next prime is 9812017. The reversal of 9811985 is 5891189.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5891189 = 1399 ⋅4211.

It can be written as a sum of positive squares in 2 ways, for example, as 2989441 + 6822544 = 1729^2 + 2612^2 .

It is a cyclic number.

It is not a de Polignac number, because 9811985 - 2² = 9811981 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (9811981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 981194 + ... + 981203.

It is an arithmetic number, because the mean of its divisors is an integer number (2943597).

Almost surely, 2^9811985 is an apocalyptic number.

It is an amenable number.

9811985 is a deficient number, since it is larger than the sum of its proper divisors (1962403).

9811985 is a wasteful number, since it uses less digits than its factorization.

9811985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1962402.

The product of its digits is 25920, while the sum is 41.

The square root of 9811985 is about 3132.4088175077. The cubic root of 9811985 is about 214.0846973092.

The spelling of 9811985 in words is "nine million, eight hundred eleven thousand, nine hundred eighty-five".