221228928 has 64 divisors (see below), whose sum is σ = 652942800. Its totient is φ = 73741824.

The previous prime is 221228923. The next prime is 221228963. The reversal of 221228928 is 829822122.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (64).

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

It is a nude number because it is divisible by every one of its digits.

It is a plaindrome in base 13.

It is a junction number, because it is equal to n+sod(n) for n = 221228892 and 221228901.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221228923) 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, 28551 + ... + 35462.

Almost surely, 2^221228928 is an apocalyptic number.

It is an amenable number.

221228928 is an abundant number, since it is smaller than the sum of its proper divisors (431713872).

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

221228928 is an equidigital number, since it uses as much as digits as its factorization.

221228928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64036 (or 64018 counting only the distinct ones).

The product of its digits is 18432, while the sum is 36.

The square root of 221228928 is about 14873.7664362461. The cubic root of 221228928 is about 604.8030486115.

The spelling of 221228928 in words is "two hundred twenty-one million, two hundred twenty-eight thousand, nine hundred twenty-eight".