66688881 has 8 divisors (see below), whose sum is σ = 101621184. Its totient is φ = 38107920.

The previous prime is 66688873. The next prime is 66688903. The reversal of 66688881 is 18888666.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 66688881 - 2³ = 66688873 is a prime.

It is a super-2 number, since 2×66688881² = 8894813698064322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66688481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1587810 + ... + 1587851.

It is an arithmetic number, because the mean of its divisors is an integer number (12702648).

Almost surely, 2^66688881 is an apocalyptic number.

It is an amenable number.

66688881 is a deficient number, since it is larger than the sum of its proper divisors (34932303).

66688881 is a wasteful number, since it uses less digits than its factorization.

66688881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3175671.

The product of its digits is 884736, while the sum is 51.

The square root of 66688881 is about 8166.3260405154. The cubic root of 66688881 is about 405.5251653910.

The spelling of 66688881 in words is "sixty-six million, six hundred eighty-eight thousand, eight hundred eighty-one".