660605681 has 2 divisors, whose sum is σ = 660605682. Its totient is φ = 660605680.

The previous prime is 660605657. The next prime is 660605707. The reversal of 660605681 is 186506066.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 656128225 + 4477456 = 25615^2 + 2116^2 .

It is a cyclic number.

It is not a de Polignac number, because 660605681 - 2²² = 656411377 is a prime.

It is a super-2 number, since 2×660605681² = 872799731538947522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (660602681) 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, 330302840 + 330302841.

It is an arithmetic number, because the mean of its divisors is an integer number (330302841).

Almost surely, 2^660605681 is an apocalyptic number.

It is an amenable number.

660605681 is a deficient number, since it is larger than the sum of its proper divisors (1).

660605681 is an equidigital number, since it uses as much as digits as its factorization.

660605681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 51840, while the sum is 38.

The square root of 660605681 is about 25702.2505045764. The cubic root of 660605681 is about 870.9250217652.

The spelling of 660605681 in words is "six hundred sixty million, six hundred five thousand, six hundred eighty-one".