9891618121 has 16 divisors (see below), whose sum is σ = 12334608000. Its totient is φ = 7706378880.

The previous prime is 9891618089. The next prime is 9891618137. The reversal of 9891618121 is 1218161989.

It is a cyclic number.

It is not a de Polignac number, because 9891618121 - 2⁵ = 9891618089 is a prime.

It is not an unprimeable number, because it can be changed into a prime (9891618161) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 744085 + ... + 757261.

It is an arithmetic number, because the mean of its divisors is an integer number (770913000).

Almost surely, 2^9891618121 is an apocalyptic number.

It is an amenable number.

9891618121 is a deficient number, since it is larger than the sum of its proper divisors (2442989879).

9891618121 is a wasteful number, since it uses less digits than its factorization.

9891618121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22944.

The product of its digits is 62208, while the sum is 46.

The square root of 9891618121 is about 99456.6142647134. The cubic root of 9891618121 is about 2146.6230108782.

The spelling of 9891618121 in words is "nine billion, eight hundred ninety-one million, six hundred eighteen thousand, one hundred twenty-one".