665121234716655 has 64 divisors (see below), whose sum is σ = 1090519387550208. Its totient is φ = 345980199720960.

The previous prime is 665121234716639. The next prime is 665121234716657. The reversal of 665121234716655 is 556617432121566.

It is not a de Polignac number, because 665121234716655 - 2⁴ = 665121234716639 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665121234716657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3836848692 + ... + 3837022038.

It is an arithmetic number, because the mean of its divisors is an integer number (17039365430472).

Almost surely, 2^{665121234716655} is an apocalyptic number.

665121234716655 is a deficient number, since it is larger than the sum of its proper divisors (425398152833553).

665121234716655 is a wasteful number, since it uses less digits than its factorization.

665121234716655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 181976.

The product of its digits is 54432000, while the sum is 60.

The spelling of 665121234716655 in words is "six hundred sixty-five trillion, one hundred twenty-one billion, two hundred thirty-four million, seven hundred sixteen thousand, six hundred fifty-five".