665641825 has 6 divisors (see below), whose sum is σ = 825395894. Its totient is φ = 532513440.

The previous prime is 665641819. The next prime is 665641829. The reversal of 665641825 is 528146566.

It can be written as a sum of positive squares in 3 ways, for example, as 102576384 + 563065441 = 10128^2 + 23729^2 .

It is not a de Polignac number, because 665641825 - 2⁹ = 665641313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665641829) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 13312812 + ... + 13312861.

Almost surely, 2^665641825 is an apocalyptic number.

It is an amenable number.

665641825 is a deficient number, since it is larger than the sum of its proper divisors (159754069).

665641825 is a wasteful number, since it uses less digits than its factorization.

665641825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26625683 (or 26625678 counting only the distinct ones).

The product of its digits is 345600, while the sum is 43.

The square root of 665641825 is about 25800.0353681928. The cubic root of 665641825 is about 873.1325943300.

The spelling of 665641825 in words is "six hundred sixty-five million, six hundred forty-one thousand, eight hundred twenty-five".