666728224 has 48 divisors (see below), whose sum is σ = 1348454520. Its totient is φ = 324311040.

The previous prime is 666728203. The next prime is 666728273. The reversal of 666728224 is 422827666.

It can be written as a sum of positive squares in 4 ways, for example, as 194100624 + 472627600 = 13932^2 + 21740^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 803842 + ... + 804670.

Almost surely, 2^666728224 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 666728224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (674227260).

666728224 is an abundant number, since it is smaller than the sum of its proper divisors (681726296).

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

666728224 is a wasteful number, since it uses less digits than its factorization.

666728224 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1493 (or 1485 counting only the distinct ones).

The product of its digits is 387072, while the sum is 43.

The square root of 666728224 is about 25821.0809998342. The cubic root of 666728224 is about 873.6073515507.

The spelling of 666728224 in words is "six hundred sixty-six million, seven hundred twenty-eight thousand, two hundred twenty-four".