221309928 has 64 divisors (see below), whose sum is σ = 702576000. Its totient is φ = 63230976.

The previous prime is 221309917. The next prime is 221309947. The reversal of 221309928 is 829903122.

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 = 221309892 and 221309901.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 71673 + ... + 74696.

It is an arithmetic number, because the mean of its divisors is an integer number (10977750).

Almost surely, 2^221309928 is an apocalyptic number.

221309928 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

221309928 is an abundant number, since it is smaller than the sum of its proper divisors (481266072).

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

221309928 is a wasteful number, since it uses less digits than its factorization.

221309928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146391 (or 146381 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 221309928 is about 14876.4891019353. The cubic root of 221309928 is about 604.8768531085.

The spelling of 221309928 in words is "two hundred twenty-one million, three hundred nine thousand, nine hundred twenty-eight".