660789665 has 4 divisors (see below), whose sum is σ = 792947604. Its totient is φ = 528631728.

The previous prime is 660789659. The next prime is 660789691. The reversal of 660789665 is 566987066.

660789665 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 566987066 = 2 ⋅283493533.

It can be written as a sum of positive squares in 2 ways, for example, as 497869969 + 162919696 = 22313^2 + 12764^2 .

It is a cyclic number.

It is not a de Polignac number, because 660789665 - 2²⁴ = 644012449 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, 66078962 + ... + 66078971.

It is an arithmetic number, because the mean of its divisors is an integer number (198236901).

Almost surely, 2^660789665 is an apocalyptic number.

It is an amenable number.

660789665 is a deficient number, since it is larger than the sum of its proper divisors (132157939).

660789665 is a wasteful number, since it uses less digits than its factorization.

660789665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132157938.

The product of its (nonzero) digits is 3265920, while the sum is 53.

The square root of 660789665 is about 25705.8293972398. The cubic root of 660789665 is about 871.0058674701.

The spelling of 660789665 in words is "six hundred sixty million, seven hundred eighty-nine thousand, six hundred sixty-five".