661005728 has 12 divisors (see below), whose sum is σ = 1301355090. Its totient is φ = 330502848.

The previous prime is 661005727. The next prime is 661005767. The reversal of 661005728 is 827500166.

It can be written as a sum of positive squares in only one way, i.e., 556393744 + 104611984 = 23588^2 + 10228^2 .

It is not an unprimeable number, because it can be changed into a prime (661005727) 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 as a sum of consecutive naturals, namely, 10328183 + ... + 10328246.

Almost surely, 2^661005728 is an apocalyptic number.

It is an amenable number.

661005728 is a deficient number, since it is larger than the sum of its proper divisors (640349362).

661005728 is a wasteful number, since it uses less digits than its factorization.

661005728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20656439 (or 20656431 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 35.

The square root of 661005728 is about 25710.0316608129. The cubic root of 661005728 is about 871.1007900770.

The spelling of 661005728 in words is "six hundred sixty-one million, five thousand, seven hundred twenty-eight".