9891661989 has 16 divisors (see below), whose sum is σ = 14405267520. Its totient is φ = 5987698560.

The previous prime is 9891661951. The next prime is 9891661999.

9891661989 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 9891661989 - 2⁷ = 9891661861 is a prime.

It is a super-2 number, since 2×9891661989² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9891661999) 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, 153432 + ... + 208145.

It is an arithmetic number, because the mean of its divisors is an integer number (900329220).

Almost surely, 2^9891661989 is an apocalyptic number.

It is an amenable number.

9891661989 is a deficient number, since it is larger than the sum of its proper divisors (4513605531).

9891661989 is a wasteful number, since it uses less digits than its factorization.

9891661989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 362420.

The product of its digits is 15116544, while the sum is 66.

The square root of 9891661989 is about 99456.8348028430. The cubic root of 9891661989 is about 2146.6261842019.

The spelling of 9891661989 in words is "nine billion, eight hundred ninety-one million, six hundred sixty-one thousand, nine hundred eighty-nine".