66810688 has 112 divisors (see below), whose sum is σ = 163860480. Its totient is φ = 26390016.

The previous prime is 66810683. The next prime is 66810701. The reversal of 66810688 is 88601866.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (112).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66810683) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 399981 + ... + 400147.

It is an arithmetic number, because the mean of its divisors is an integer number (1463040).

Almost surely, 2^66810688 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 66810688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (81930240).

66810688 is an abundant number, since it is smaller than the sum of its proper divisors (97049792).

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

66810688 is a wasteful number, since it uses less digits than its factorization.

66810688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 252 (or 242 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 43.

The square root of 66810688 is about 8173.7805206648. The cubic root of 66810688 is about 405.7719119740.

It can be divided in two parts, 668 and 10688, that multiplied together give a square (7139584 = 2672²).

The spelling of 66810688 in words is "sixty-six million, eight hundred ten thousand, six hundred eighty-eight".