6665121664 has 16 divisors (see below), whose sum is σ = 13278172320. Its totient is φ = 3332560768.

The previous prime is 6665121607. The next prime is 6665121679. The reversal of 6665121664 is 4661215666.

It is a tau number, because it is divible by the number of its divisors (16).

It is a self number, because there is not a number n which added to its sum of digits gives 6665121664.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 26035504 + ... + 26035759.

It is an arithmetic number, because the mean of its divisors is an integer number (829885770).

Almost surely, 2^6665121664 is an apocalyptic number.

6665121664 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

6665121664 is a deficient number, since it is larger than the sum of its proper divisors (6613050656).

6665121664 is an equidigital number, since it uses as much as digits as its factorization.

6665121664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52071277 (or 52071265 counting only the distinct ones).

The product of its digits is 311040, while the sum is 43.

The square root of 6665121664 is about 81640.1963740901. The cubic root of 6665121664 is about 1881.9266562118.

The spelling of 6665121664 in words is "six billion, six hundred sixty-five million, one hundred twenty-one thousand, six hundred sixty-four".