999808666 has 16 divisors (see below), whose sum is σ = 1590576768. Its totient is φ = 470329200.

The previous prime is 999808661. The next prime is 999808673. The reversal of 999808666 is 666808999.

It is a Harshad number since it is a multiple of its sum of digits (61).

999808666 is a strobogrammatic number because it is the same when read upside-down.

It is not an unprimeable number, because it can be changed into a prime (999808661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 175350 + ... + 180961.

It is an arithmetic number, because the mean of its divisors is an integer number (99411048).

Almost surely, 2^999808666 is an apocalyptic number.

999808666 is a deficient number, since it is larger than the sum of its proper divisors (590768102).

999808666 is a wasteful number, since it uses less digits than its factorization.

999808666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 356397.

The product of its (nonzero) digits is 10077696, while the sum is 61.

The square root of 999808666 is about 31619.7512007922. The cubic root of 999808666 is about 999.9362179319.

The spelling of 999808666 in words is "nine hundred ninety-nine million, eight hundred eight thousand, six hundred sixty-six".