166551221656 has 64 divisors (see below), whose sum is σ = 320856606720. Its totient is φ = 81021064320.

The previous prime is 166551221623. The next prime is 166551221663. The reversal of 166551221656 is 656122155661.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 65492721 + ... + 65495263.

It is an arithmetic number, because the mean of its divisors is an integer number (5013384480).

Almost surely, 2^166551221656 is an apocalyptic number.

It is an amenable number.

166551221656 is a deficient number, since it is larger than the sum of its proper divisors (154305385064).

166551221656 is a wasteful number, since it uses less digits than its factorization.

166551221656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4016 (or 4012 counting only the distinct ones).

The product of its digits is 648000, while the sum is 46.

The spelling of 166551221656 in words is "one hundred sixty-six billion, five hundred fifty-one million, two hundred twenty-one thousand, six hundred fifty-six".