665728687 has 12 divisors (see below), whose sum is σ = 763285680. Its totient is φ = 578368128.

The previous prime is 665728681. The next prime is 665728691. The reversal of 665728687 is 786827566.

It is not a de Polignac number, because 665728687 - 2⁷ = 665728559 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665728681) 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 11 ways as a sum of consecutive naturals, for example, 112987 + ... + 118732.

It is an arithmetic number, because the mean of its divisors is an integer number (63607140).

Almost surely, 2^665728687 is an apocalyptic number.

665728687 is a deficient number, since it is larger than the sum of its proper divisors (97556993).

665728687 is a wasteful number, since it uses less digits than its factorization.

665728687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 231762 (or 231749 counting only the distinct ones).

The product of its digits is 6773760, while the sum is 55.

The square root of 665728687 is about 25801.7186830645. The cubic root of 665728687 is about 873.1705720841.

It can be divided in two parts, 6657 and 28687, that added together give a square (35344 = 188²).

The spelling of 665728687 in words is "six hundred sixty-five million, seven hundred twenty-eight thousand, six hundred eighty-seven".