221435728 has 40 divisors (see below), whose sum is σ = 466200320. Its totient is φ = 101502720.

The previous prime is 221435717. The next prime is 221435777. The reversal of 221435728 is 827534122.

It is a happy number.

221435728 is nontrivially palindromic in base 3.

221435728 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 = 221435693 and 221435702.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2325 + ... + 21172.

It is an arithmetic number, because the mean of its divisors is an integer number (11655008).

Almost surely, 2^221435728 is an apocalyptic number.

It is an amenable number.

221435728 is an abundant number, since it is smaller than the sum of its proper divisors (244764592).

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

221435728 is a wasteful number, since it uses less digits than its factorization.

221435728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23555 (or 23549 counting only the distinct ones).

The product of its digits is 26880, while the sum is 34.

The square root of 221435728 is about 14880.7166494091. The cubic root of 221435728 is about 604.9914421757.

The spelling of 221435728 in words is "two hundred twenty-one million, four hundred thirty-five thousand, seven hundred twenty-eight".