221538824 has 64 divisors (see below), whose sum is σ = 464970240. Its totient is φ = 98300160.

The previous prime is 221538809. The next prime is 221538827. The reversal of 221538824 is 428835122.

221538824 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (221538827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 297797 + ... + 298539.

It is an arithmetic number, because the mean of its divisors is an integer number (7265160).

Almost surely, 2^221538824 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 221538824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (232485120).

221538824 is an abundant number, since it is smaller than the sum of its proper divisors (243431416).

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

221538824 is a wasteful number, since it uses less digits than its factorization.

221538824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 870 (or 866 counting only the distinct ones).

The product of its digits is 30720, while the sum is 35.

The square root of 221538824 is about 14884.1803267765. The cubic root of 221538824 is about 605.0853182047.

The spelling of 221538824 in words is "two hundred twenty-one million, five hundred thirty-eight thousand, eight hundred twenty-four".