221666656 has 12 divisors (see below), whose sum is σ = 436406292. Its totient is φ = 110833312.

The previous prime is 221666629. The next prime is 221666659. The reversal of 221666656 is 656666122.

221666656 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×221666656² = 98272212764444672, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221666659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3463510 + ... + 3463573.

It is an arithmetic number, because the mean of its divisors is an integer number (36367191).

Almost surely, 2^221666656 is an apocalyptic number.

It is an amenable number.

221666656 is a deficient number, since it is larger than the sum of its proper divisors (214739636).

221666656 is an equidigital number, since it uses as much as digits as its factorization.

221666656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6927093 (or 6927085 counting only the distinct ones).

The product of its digits is 155520, while the sum is 40.

The square root of 221666656 is about 14888.4739311993. The cubic root of 221666656 is about 605.2016776347.

The spelling of 221666656 in words is "two hundred twenty-one million, six hundred sixty-six thousand, six hundred fifty-six".