66666688 has 56 divisors (see below), whose sum is σ = 145261584. Its totient is φ = 30105600.

The previous prime is 66666683. The next prime is 66666713. The reversal of 66666688 is 88666666.

It is a plaindrome in base 10.

It is a zygodrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (66666683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 197656 + ... + 197992.

Almost surely, 2^66666688 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66666688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (72630792).

66666688 is an abundant number, since it is smaller than the sum of its proper divisors (78594896).

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

66666688 is a wasteful number, since it uses less digits than its factorization.

66666688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 641 (or 631 counting only the distinct ones).

The product of its digits is 2985984, while the sum is 52.

The square root of 66666688 is about 8164.9671156717. The cubic root of 66666688 is about 405.4801762894.

The spelling of 66666688 in words is "sixty-six million, six hundred sixty-six thousand, six hundred eighty-eight".