665655993 has 12 divisors (see below), whose sum is σ = 970013460. Its totient is φ = 439842816.

The previous prime is 665655989. The next prime is 665655997. The reversal of 665655993 is 399556566.

It is an interprime number because it is at equal distance from previous prime (665655989) and next prime (665655997).

It can be written as a sum of positive squares in 2 ways, for example, as 118657449 + 546998544 = 10893^2 + 23388^2 .

It is not a de Polignac number, because 665655993 - 2² = 665655989 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (665655997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 326248 + ... + 328281.

It is an arithmetic number, because the mean of its divisors is an integer number (80834455).

Almost surely, 2^665655993 is an apocalyptic number.

It is an amenable number.

665655993 is a deficient number, since it is larger than the sum of its proper divisors (304357467).

665655993 is a wasteful number, since it uses less digits than its factorization.

665655993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 654648 (or 654645 counting only the distinct ones).

The product of its digits is 6561000, while the sum is 54.

The square root of 665655993 is about 25800.3099399988. The cubic root of 665655993 is about 873.1387890804.

The spelling of 665655993 in words is "six hundred sixty-five million, six hundred fifty-five thousand, nine hundred ninety-three".