666888999 has 64 divisors (see below), whose sum is σ = 1108992000. Its totient is φ = 347960448.

The previous prime is 666888997. The next prime is 666889001. The reversal of 666888999 is 999888666.

It is an interprime number because it is at equal distance from previous prime (666888997) and next prime (666889001).

It is not a de Polignac number, because 666888999 - 2¹ = 666888997 is a prime.

666888999 is a strobogrammatic number because it is the same when read upside-down.

It is a plaindrome in base 10.

It is a zygodrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666888997) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2937724 + ... + 2937950.

It is an arithmetic number, because the mean of its divisors is an integer number (17328000).

Almost surely, 2^666888999 is an apocalyptic number.

666888999 is a deficient number, since it is larger than the sum of its proper divisors (442103001).

666888999 is a wasteful number, since it uses less digits than its factorization.

666888999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 492.

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

The square root of 666888999 is about 25824.1940629325. The cubic root of 666888999 is about 873.6775665342.

The spelling of 666888999 in words is "six hundred sixty-six million, eight hundred eighty-eight thousand, nine hundred ninety-nine".