66606660 has 144 divisors (see below), whose sum is σ = 211878576. Its totient is φ = 16920576.

The previous prime is 66606611. The next prime is 66606667. The reversal of 66606660 is 6660666.

66606660 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 8 ways, for example, as 3594816 + 63011844 = 1896^2 + 7938^2 .

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

It is not an unprimeable number, because it can be changed into a prime (66606667) 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 47 ways as a sum of consecutive naturals, for example, 486112 + ... + 486248.

It is an arithmetic number, because the mean of its divisors is an integer number (1471379).

Almost surely, 2^66606660 is an apocalyptic number.

66606660 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 66606660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (105939288).

66606660 is an abundant number, since it is smaller than the sum of its proper divisors (145271916).

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

66606660 is a wasteful number, since it uses less digits than its factorization.

66606660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 262 (or 257 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 36.

The square root of 66606660 is about 8161.2903391559. The cubic root of 66606660 is about 405.3584389627.

The spelling of 66606660 in words is "sixty-six million, six hundred six thousand, six hundred sixty".