9661688921 has 4 divisors (see below), whose sum is σ = 9662005200. Its totient is φ = 9661372644.

The previous prime is 9661688891. The next prime is 9661688929. The reversal of 9661688921 is 1298861669.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 9661688921 - 2³⁰ = 8587947097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9661688929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 106751 + ... + 175268.

It is an arithmetic number, because the mean of its divisors is an integer number (2415501300).

Almost surely, 2^9661688921 is an apocalyptic number.

It is an amenable number.

9661688921 is a deficient number, since it is larger than the sum of its proper divisors (316279).

9661688921 is a wasteful number, since it uses less digits than its factorization.

9661688921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 316278.

The product of its digits is 2239488, while the sum is 56.

The square root of 9661688921 is about 98293.8905578572. The cubic root of 9661688921 is about 2129.8598011419.

The spelling of 9661688921 in words is "nine billion, six hundred sixty-one million, six hundred eighty-eight thousand, nine hundred twenty-one".