221388928 has 32 divisors (see below), whose sum is σ = 442326060. Its totient is φ = 110373888.

The previous prime is 221388907. The next prime is 221388953. The reversal of 221388928 is 829883122.

It can be written as a sum of positive squares in 2 ways, for example, as 218803264 + 2585664 = 14792^2 + 1608^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45426 + ... + 50062.

Almost surely, 2^221388928 is an apocalyptic number.

It is an amenable number.

221388928 is a deficient number, since it is larger than the sum of its proper divisors (220937132).

221388928 is an equidigital number, since it uses as much as digits as its factorization.

221388928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5024 (or 5012 counting only the distinct ones).

The product of its digits is 110592, while the sum is 43.

The square root of 221388928 is about 14879.1440614035. The cubic root of 221388928 is about 604.9488179273.

The spelling of 221388928 in words is "two hundred twenty-one million, three hundred eighty-eight thousand, nine hundred twenty-eight".