221641664 has 28 divisors (see below), whose sum is σ = 454990200. Its totient is φ = 106998528.

The previous prime is 221641643. The next prime is 221641681. The reversal of 221641664 is 466146122.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a self number, because there is not a number n which added to its sum of digits gives 221641664.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 57854 + ... + 61565.

It is an arithmetic number, because the mean of its divisors is an integer number (16249650).

Almost surely, 2^221641664 is an apocalyptic number.

It is an amenable number.

221641664 is an abundant number, since it is smaller than the sum of its proper divisors (233348536).

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

221641664 is a wasteful number, since it uses less digits than its factorization.

221641664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 119460 (or 119450 counting only the distinct ones).

The product of its digits is 13824, while the sum is 32.

The square root of 221641664 is about 14887.6346005670. The cubic root of 221641664 is about 605.1789321166.

Adding to 221641664 its reverse (466146122), we get a palindrome (687787786).

The spelling of 221641664 in words is "two hundred twenty-one million, six hundred forty-one thousand, six hundred sixty-four".