665605659 has 4 divisors (see below), whose sum is σ = 887474216. Its totient is φ = 443737104.

The previous prime is 665605639. The next prime is 665605693. The reversal of 665605659 is 956506566.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 665605659 - 2¹⁷ = 665474587 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665605639) 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, 110934274 + ... + 110934279.

It is an arithmetic number, because the mean of its divisors is an integer number (221868554).

Almost surely, 2^665605659 is an apocalyptic number.

665605659 is a deficient number, since it is larger than the sum of its proper divisors (221868557).

665605659 is a wasteful number, since it uses less digits than its factorization.

665605659 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221868556.

The product of its (nonzero) digits is 1458000, while the sum is 48.

The square root of 665605659 is about 25799.3344681602. The cubic root of 665605659 is about 873.1167808779.

The spelling of 665605659 in words is "six hundred sixty-five million, six hundred five thousand, six hundred fifty-nine".