999888666 has 32 divisors (see below), whose sum is σ = 2347232640. Its totient is φ = 277960896.

The previous prime is 999888613. The next prime is 999888667. The reversal of 999888666 is 666888999.

999888666 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 a self number, because there is not a number n which added to its sum of digits gives 999888666.

It is not an unprimeable number, because it can be changed into a prime (999888667) 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, 320161 + ... + 323268.

It is an arithmetic number, because the mean of its divisors is an integer number (73351020).

Almost surely, 2^999888666 is an apocalyptic number.

999888666 is an abundant number, since it is smaller than the sum of its proper divisors (1347343974).

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

999888666 is a wasteful number, since it uses less digits than its factorization.

999888666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 643478.

The product of its digits is 80621568, while the sum is 69.

The square root of 999888666 is about 31621.0162075794. The cubic root of 999888666 is about 999.9628872893.

The spelling of 999888666 in words is "nine hundred ninety-nine million, eight hundred eighty-eight thousand, six hundred sixty-six".