665665001665 has 4 divisors (see below), whose sum is σ = 798798002004. Its totient is φ = 532532001328.

The previous prime is 665665001647. The next prime is 665665001681. The reversal of 665665001665 is 566100566566.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 566100566566 = 2 ⋅283050283283.

It can be written as a sum of positive squares in 2 ways, for example, as 523433439169 + 142231562496 = 723487^2 + 377136^2 .

It is a cyclic number.

It is not a de Polignac number, because 665665001665 - 2²³ = 665656613057 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66566500162 + ... + 66566500171.

It is an arithmetic number, because the mean of its divisors is an integer number (199699500501).

Almost surely, 2^665665001665 is an apocalyptic number.

It is an amenable number.

665665001665 is a deficient number, since it is larger than the sum of its proper divisors (133133000339).

665665001665 is a wasteful number, since it uses less digits than its factorization.

665665001665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133133000338.

The product of its (nonzero) digits is 5832000, while the sum is 52.

The spelling of 665665001665 in words is "six hundred sixty-five billion, six hundred sixty-five million, one thousand, six hundred sixty-five".