666289728 has 168 divisors, whose sum is σ = 2079427896. Its totient is φ = 202752000.

The previous prime is 666289717. The next prime is 666289733. The reversal of 666289728 is 827982666.

It can be written as a sum of positive squares in 4 ways, for example, as 63489024 + 602800704 = 7968^2 + 24552^2 .

It is a super-3 number, since 3×666289728³ (a number of 27 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 755848 + ... + 756728.

It is an arithmetic number, because the mean of its divisors is an integer number (12377547).

Almost surely, 2^666289728 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 666289728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1039713948).

666289728 is an abundant number, since it is smaller than the sum of its proper divisors (1413138168).

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

666289728 is a wasteful number, since it uses less digits than its factorization.

666289728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1013 (or 1000 counting only the distinct ones).

The product of its digits is 3483648, while the sum is 54.

The square root of 666289728 is about 25812.5885567488. The cubic root of 666289728 is about 873.4157905686.

The spelling of 666289728 in words is "six hundred sixty-six million, two hundred eighty-nine thousand, seven hundred twenty-eight".