665640793 has 4 divisors (see below), whose sum is σ = 665873460. Its totient is φ = 665408128.

The previous prime is 665640761. The next prime is 665640809. The reversal of 665640793 is 397046566.

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

It can be written as a sum of positive squares in 2 ways, for example, as 110944089 + 554696704 = 10533^2 + 23552^2 .

It is a cyclic number.

It is not a de Polignac number, because 665640793 - 2⁵ = 665640761 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665640293) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111988 + ... + 117781.

It is an arithmetic number, because the mean of its divisors is an integer number (166468365).

Almost surely, 2^665640793 is an apocalyptic number.

It is an amenable number.

665640793 is a deficient number, since it is larger than the sum of its proper divisors (232667).

665640793 is a wasteful number, since it uses less digits than its factorization.

665640793 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232666.

The product of its (nonzero) digits is 816480, while the sum is 46.

The square root of 665640793 is about 25800.0153682125. The cubic root of 665640793 is about 873.1321430997.

The spelling of 665640793 in words is "six hundred sixty-five million, six hundred forty thousand, seven hundred ninety-three".