221506656 has 180 divisors, whose sum is σ = 700911036. Its totient is φ = 61246080.

The previous prime is 221506609. The next prime is 221506667. The reversal of 221506656 is 656605122.

It is a happy number.

221506656 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 7145361 + ... + 7145391.

Almost surely, 2^221506656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221506656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (350455518).

221506656 is an abundant number, since it is smaller than the sum of its proper divisors (479404380).

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

221506656 is an frugal number, since it uses more digits than its factorization.

221506656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103 (or 43 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 33.

The square root of 221506656 is about 14883.0996771506. The cubic root of 221506656 is about 605.0560301453.

Multiplying 221506656 by its product of nonzero digits (21600), we get a square (4784543769600 = 2187360²).

It can be divided in two parts, 2215066 and 56, that added together give a palindrome (2215122).

The spelling of 221506656 in words is "two hundred twenty-one million, five hundred six thousand, six hundred fifty-six".