9989863661 has 4 divisors (see below), whose sum is σ = 9995449500. Its totient is φ = 9984277824.

The previous prime is 9989863627. The next prime is 9989863747. The reversal of 9989863661 is 1663689899.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1663689899 = 3049 ⋅545651.

It can be written as a sum of positive squares in 2 ways, for example, as 8334594436 + 1655269225 = 91294^2 + 40685^2 .

It is a cyclic number.

It is not a de Polignac number, because 9989863661 - 2¹⁰ = 9989862637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9989863621) 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, 2790236 + ... + 2793813.

It is an arithmetic number, because the mean of its divisors is an integer number (2498862375).

Almost surely, 2^9989863661 is an apocalyptic number.

It is an amenable number.

9989863661 is a deficient number, since it is larger than the sum of its proper divisors (5585839).

9989863661 is a wasteful number, since it uses less digits than its factorization.

9989863661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5585838.

The product of its digits is 30233088, while the sum is 65.

The square root of 9989863661 is about 99949.3054553157. The cubic root of 9989863661 is about 2153.7065079274.

The spelling of 9989863661 in words is "nine billion, nine hundred eighty-nine million, eight hundred sixty-three thousand, six hundred sixty-one".