221916728 has 32 divisors (see below), whose sum is σ = 455051520. Its totient is φ = 100620000.

The previous prime is 221916727. The next prime is 221916731. The reversal of 221916728 is 827619122.

221916728 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 221916691 and 221916700.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221916727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35003 + ... + 40853.

It is an arithmetic number, because the mean of its divisors is an integer number (14220360).

Almost surely, 2^221916728 is an apocalyptic number.

It is an amenable number.

221916728 is an abundant number, since it is smaller than the sum of its proper divisors (233134792).

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

221916728 is a wasteful number, since it uses less digits than its factorization.

221916728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6299 (or 6295 counting only the distinct ones).

The product of its digits is 24192, while the sum is 38.

The square root of 221916728 is about 14896.8697383041. The cubic root of 221916728 is about 605.4291770696.

The spelling of 221916728 in words is "two hundred twenty-one million, nine hundred sixteen thousand, seven hundred twenty-eight".