221666637485856 has 24 divisors (see below), whose sum is σ = 581874923400624. Its totient is φ = 73888879161920.

The previous prime is 221666637485849. The next prime is 221666637485921. The reversal of 221666637485856 is 658584736666122.

It is a tau number, because it is divible by the number of its divisors (24).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1154513736810 + ... + 1154513737001.

It is an arithmetic number, because the mean of its divisors is an integer number (24244788475026).

Almost surely, 2^{221666637485856} is an apocalyptic number.

It is an amenable number.

221666637485856 is an abundant number, since it is smaller than the sum of its proper divisors (360208285914768).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

221666637485856 is a wasteful number, since it uses less digits than its factorization.

221666637485856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2309027473824 (or 2309027473816 counting only the distinct ones).

The product of its digits is 4180377600, while the sum is 75.

The spelling of 221666637485856 in words is "two hundred twenty-one trillion, six hundred sixty-six billion, six hundred thirty-seven million, four hundred eighty-five thousand, eight hundred fifty-six".