221824728 has 48 divisors (see below), whose sum is σ = 601473600. Its totient is φ = 73855680.

The previous prime is 221824727. The next prime is 221824751. The reversal of 221824728 is 827428122.

221824728 is a `hidden beast` number, since 2 + 2 + 182 + 472 + 8 = 666.

221824728 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 221824692 and 221824701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221824727) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 102538 + ... + 104678.

It is an arithmetic number, because the mean of its divisors is an integer number (12530700).

Almost surely, 2^221824728 is an apocalyptic number.

It is an amenable number.

221824728 is an abundant number, since it is smaller than the sum of its proper divisors (379648872).

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

221824728 is a wasteful number, since it uses less digits than its factorization.

221824728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3592 (or 3585 counting only the distinct ones).

The product of its digits is 28672, while the sum is 36.

The square root of 221824728 is about 14893.7815211584. The cubic root of 221824728 is about 605.3455012637.

The spelling of 221824728 in words is "two hundred twenty-one million, eight hundred twenty-four thousand, seven hundred twenty-eight".