665621175811 has 4 divisors (see below), whose sum is σ = 665637219072. Its totient is φ = 665605132552.

The previous prime is 665621175809. The next prime is 665621175841. The reversal of 665621175811 is 118571126566.

665621175811 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.

It is a cyclic number.

It is not a de Polignac number, because 665621175811 - 2¹ = 665621175809 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665621175841) 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, 7959235 + ... + 8042428.

It is an arithmetic number, because the mean of its divisors is an integer number (166409304768).

Almost surely, 2^665621175811 is an apocalyptic number.

665621175811 is a deficient number, since it is larger than the sum of its proper divisors (16043261).

665621175811 is a wasteful number, since it uses less digits than its factorization.

665621175811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16043260.

The product of its digits is 604800, while the sum is 49.

The spelling of 665621175811 in words is "six hundred sixty-five billion, six hundred twenty-one million, one hundred seventy-five thousand, eight hundred eleven".