665820539 has 2 divisors, whose sum is σ = 665820540. Its totient is φ = 665820538.

The previous prime is 665820523. The next prime is 665820593. The reversal of 665820539 is 935028566.

It is a happy number.

Together with next prime (665820593) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 665820539 - 2⁴ = 665820523 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 665820539.

It is not a weakly prime, because it can be changed into another prime (665820509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332910269 + 332910270.

It is an arithmetic number, because the mean of its divisors is an integer number (332910270).

Almost surely, 2^665820539 is an apocalyptic number.

665820539 is a deficient number, since it is larger than the sum of its proper divisors (1).

665820539 is an equidigital number, since it uses as much as digits as its factorization.

665820539 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 388800, while the sum is 44.

The square root of 665820539 is about 25803.4985806189. The cubic root of 665820539 is about 873.2107279698.

The spelling of 665820539 in words is "six hundred sixty-five million, eight hundred twenty thousand, five hundred thirty-nine".