66688 has 16 divisors (see below), whose sum is σ = 133110. Its totient is φ = 33280.

The previous prime is 66683. The next prime is 66697. The reversal of 66688 is 88666.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 61504 + 5184 = 248^2 + 72^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is a plaindrome in base 10 and base 13.

It is a zygodrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (66683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (3) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 133 + ... + 388.

2⁶⁶⁶⁸⁸ is an apocalyptic number.

It is an amenable number.

66688 is a deficient number, since it is larger than the sum of its proper divisors (66422).

66688 is an equidigital number, since it uses as much as digits as its factorization.

66688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 535 (or 523 counting only the distinct ones).

The product of its digits is 13824, while the sum is 34.

The square root of 66688 is about 258.2401982651. The cubic root of 66688 is about 40.5523379640.

The spelling of 66688 in words is "sixty-six thousand, six hundred eighty-eight".