660405681 has 48 divisors (see below), whose sum is σ = 1091510784. Its totient is φ = 381169152.

The previous prime is 660405671. The next prime is 660405709. The reversal of 660405681 is 186504066.

It is not a de Polignac number, because 660405681 - 2⁹ = 660405169 is a prime.

It is a super-2 number, since 2×660405681² = 872271326994147522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (660405631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1087680 + ... + 1088286.

It is an arithmetic number, because the mean of its divisors is an integer number (22739808).

Almost surely, 2^660405681 is an apocalyptic number.

It is an amenable number.

660405681 is a deficient number, since it is larger than the sum of its proper divisors (431105103).

660405681 is a wasteful number, since it uses less digits than its factorization.

660405681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1190 (or 1187 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 660405681 is about 25698.3595001704. The cubic root of 660405681 is about 870.8371213274.

The spelling of 660405681 in words is "six hundred sixty million, four hundred five thousand, six hundred eighty-one".