66220728 has 64 divisors (see below), whose sum is σ = 190018560. Its totient is φ = 18838656.

The previous prime is 66220727. The next prime is 66220733. The reversal of 66220728 is 82702266.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66220727) 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, 45825 + ... + 47247.

It is an arithmetic number, because the mean of its divisors is an integer number (2969040).

Almost surely, 2^66220728 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 66220728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (95009280).

66220728 is an abundant number, since it is smaller than the sum of its proper divisors (123797832).

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

66220728 is a wasteful number, since it uses less digits than its factorization.

66220728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1716 (or 1712 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 33.

The square root of 66220728 is about 8137.6119347140. The cubic root of 66220728 is about 404.5740133064.

The spelling of 66220728 in words is "sixty-six million, two hundred twenty thousand, seven hundred twenty-eight".