665603709 has 4 divisors (see below), whose sum is σ = 887471616. Its totient is φ = 443735804.

The previous prime is 665603699. The next prime is 665603713. The reversal of 665603709 is 907306566.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 665603709 - 2⁷ = 665603581 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665603749) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 110933949 + ... + 110933954.

It is an arithmetic number, because the mean of its divisors is an integer number (221867904).

Almost surely, 2^665603709 is an apocalyptic number.

It is an amenable number.

665603709 is a deficient number, since it is larger than the sum of its proper divisors (221867907).

665603709 is a wasteful number, since it uses less digits than its factorization.

665603709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221867906.

The product of its (nonzero) digits is 204120, while the sum is 42.

The square root of 665603709 is about 25799.2966764600. The cubic root of 665603709 is about 873.1159282312.

The spelling of 665603709 in words is "six hundred sixty-five million, six hundred three thousand, seven hundred nine".