221643612 has 18 divisors (see below), whose sum is σ = 560265888. Its totient is φ = 73881192.

The previous prime is 221643601. The next prime is 221643641. The reversal of 221643612 is 216346122.

221643612 is a `hidden beast` number, since 2 + 2 + 1 + 6 + 43 + 612 = 666.

221643612 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (18).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3078348 + ... + 3078419.

Almost surely, 2^221643612 is an apocalyptic number.

It is an amenable number.

221643612 is an abundant number, since it is smaller than the sum of its proper divisors (338622276).

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

221643612 is a wasteful number, since it uses less digits than its factorization.

221643612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6156777 (or 6156772 counting only the distinct ones).

The product of its digits is 3456, while the sum is 27.

The square root of 221643612 is about 14887.7000238452. The cubic root of 221643612 is about 605.1807050762.

Adding to 221643612 its reverse (216346122), we get a palindrome (437989734).

The spelling of 221643612 in words is "two hundred twenty-one million, six hundred forty-three thousand, six hundred twelve".