9666811221 has 16 divisors (see below), whose sum is σ = 13059605760. Its totient is φ = 6359371200.

The previous prime is 9666811211. The next prime is 9666811223. The reversal of 9666811221 is 1221186669.

It is not a de Polignac number, because 9666811221 - 2¹⁹ = 9666286933 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9666811223) 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, 447571 + ... + 468671.

It is an arithmetic number, because the mean of its divisors is an integer number (816225360).

Almost surely, 2^9666811221 is an apocalyptic number.

It is an amenable number.

9666811221 is a deficient number, since it is larger than the sum of its proper divisors (3392794539).

9666811221 is a wasteful number, since it uses less digits than its factorization.

9666811221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23116.

The product of its digits is 62208, while the sum is 42.

The square root of 9666811221 is about 98319.9431499022. The cubic root of 9666811221 is about 2130.2361278041.

The spelling of 9666811221 in words is "nine billion, six hundred sixty-six million, eight hundred eleven thousand, two hundred twenty-one".