9999966666 has 32 divisors (see below), whose sum is σ = 20563474176. Its totient is φ = 3240000000.

The previous prime is 9999966659. The next prime is 9999966667. The reversal of 9999966666 is 6666699999.

It is a super-5 number, since 5×9999966666⁵ (a number of 51 digits) contains 55555 as substring. Note that it is a super-d number also for d = 2.

9999966666 is a strobogrammatic number because it is the same when read upside-down.

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (9999966667) 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, 8335 + ... + 141666.

It is an arithmetic number, because the mean of its divisors is an integer number (642608568).

Almost surely, 2^9999966666 is an apocalyptic number.

9999966666 is an abundant number, since it is smaller than the sum of its proper divisors (10563507510).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

9999966666 is a wasteful number, since it uses less digits than its factorization.

9999966666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150318.

The product of its digits is 459165024, while the sum is 75.

The square root of 9999966666 is about 99999.8333298611. The cubic root of 9999966666 is about 2154.4322961650.

The spelling of 9999966666 in words is "nine billion, nine hundred ninety-nine million, nine hundred sixty-six thousand, six hundred sixty-six".