9999900666 has 24 divisors (see below), whose sum is σ = 24761659104. Its totient is φ = 2857114440.

The previous prime is 9999900587. The next prime is 9999900679. The reversal of 9999900666 is 6660099999.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a zygodrome in base 10.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 39682020 + ... + 39682271.

It is an arithmetic number, because the mean of its divisors is an integer number (1031735796).

Almost surely, 2^9999900666 is an apocalyptic number.

9999900666 is an abundant number, since it is smaller than the sum of its proper divisors (14761758438).

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

9999900666 is a wasteful number, since it uses less digits than its factorization.

9999900666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79364306 (or 79364303 counting only the distinct ones).

The product of its (nonzero) digits is 12754584, while the sum is 63.

The square root of 9999900666 is about 99999.5033287666. The cubic root of 9999900666 is about 2154.4275563877.

The spelling of 9999900666 in words is "nine billion, nine hundred ninety-nine million, nine hundred thousand, six hundred sixty-six".