665121566 has 8 divisors (see below), whose sum is σ = 1056369600. Its totient is φ = 312998368.

The previous prime is 665121559. The next prime is 665121571.

665121566 is nontrivially palindromic in base 10.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9781166 + ... + 9781233.

It is an arithmetic number, because the mean of its divisors is an integer number (132046200).

Almost surely, 2^665121566 is an apocalyptic number.

665121566 is a deficient number, since it is larger than the sum of its proper divisors (391248034).

665121566 is a wasteful number, since it uses less digits than its factorization.

665121566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19562418.

The product of its digits is 64800, while the sum is 38.

The square root of 665121566 is about 25789.9508723844. The cubic root of 665121566 is about 872.9050578022.

The spelling of 665121566 in words is "six hundred sixty-five million, one hundred twenty-one thousand, five hundred sixty-six".