665821675 has 18 divisors (see below), whose sum is σ = 845894148. Its totient is φ = 519608880.

The previous prime is 665821661. The next prime is 665821699. The reversal of 665821675 is 576128566.

It is not a de Polignac number, because 665821675 - 2¹⁷ = 665690603 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 17 ways as a sum of consecutive naturals, for example, 845632 + ... + 846418.

Almost surely, 2^665821675 is an apocalyptic number.

665821675 is a deficient number, since it is larger than the sum of its proper divisors (180072473).

665821675 is an frugal number, since it uses more digits than its factorization.

665821675 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1627 (or 835 counting only the distinct ones).

The product of its digits is 604800, while the sum is 46.

The square root of 665821675 is about 25803.5205931284. The cubic root of 665821675 is about 873.2112245835.

The spelling of 665821675 in words is "six hundred sixty-five million, eight hundred twenty-one thousand, six hundred seventy-five".