66688020 has 108 divisors (see below), whose sum is σ = 235344564. Its totient is φ = 15240960.

The previous prime is 66688009. The next prime is 66688021. The reversal of 66688020 is 2088666.

66688020 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 19820304 + 46867716 = 4452^2 + 6846^2 .

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66688021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 5040 + ... + 12600.

Almost surely, 2^66688020 is an apocalyptic number.

66688020 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66688020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117672282).

66688020 is an abundant number, since it is smaller than the sum of its proper divisors (168656544).

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

66688020 is a wasteful number, since it uses less digits than its factorization.

66688020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7590 (or 7578 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 36.

The square root of 66688020 is about 8166.2733238608. The cubic root of 66688020 is about 405.5234201791.

The spelling of 66688020 in words is "sixty-six million, six hundred eighty-eight thousand, twenty".