221561824 has 48 divisors (see below), whose sum is σ = 478396800. Its totient is φ = 100172160.

The previous prime is 221561779. The next prime is 221561839. The reversal of 221561824 is 428165122.

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 7 ways as a sum of consecutive naturals, for example, 68467 + ... + 71629.

It is an arithmetic number, because the mean of its divisors is an integer number (9966600).

Almost surely, 2^221561824 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 221561824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (239198400).

221561824 is an abundant number, since it is smaller than the sum of its proper divisors (256834976).

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

221561824 is a wasteful number, since it uses less digits than its factorization.

221561824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3383 (or 3375 counting only the distinct ones).

The product of its digits is 7680, while the sum is 31.

The square root of 221561824 is about 14884.9529391261. The cubic root of 221561824 is about 605.1062573197.

The spelling of 221561824 in words is "two hundred twenty-one million, five hundred sixty-one thousand, eight hundred twenty-four".