666688888889999 has 4 divisors (see below), whose sum is σ = 666778269362520. Its totient is φ = 666599508417480.

The previous prime is 666688888889987. The next prime is 666688888890019. The reversal of 666688888889999 is 999988888886666.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666688888889999 is a prime.

666688888889999 is a strobogrammatic number because it is the same when read upside-down.

It is a Duffinian number.

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 (666688888889929) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44690225072 + ... + 44690239989.

It is an arithmetic number, because the mean of its divisors is an integer number (166694567340630).

Almost surely, 2^{666688888889999} is an apocalyptic number.

666688888889999 is a deficient number, since it is larger than the sum of its proper divisors (89380472521).

666688888889999 is an equidigital number, since it uses as much as digits as its factorization.

666688888889999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89380472520.

The product of its digits is 17832200896512, while the sum is 116.

The spelling of 666688888889999 in words is "six hundred sixty-six trillion, six hundred eighty-eight billion, eight hundred eighty-eight million, eight hundred eighty-nine thousand, nine hundred ninety-nine".