221538768 has 80 divisors (see below), whose sum is σ = 627287232. Its totient is φ = 66816000.

The previous prime is 221538761. The next prime is 221538773. The reversal of 221538768 is 867835122.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221538761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 126378 + ... + 128118.

Almost surely, 2^221538768 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221538768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (313643616).

221538768 is an abundant number, since it is smaller than the sum of its proper divisors (405748464).

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

221538768 is a wasteful number, since it uses less digits than its factorization.

221538768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2004 (or 1998 counting only the distinct ones).

The product of its digits is 161280, while the sum is 42.

The square root of 221538768 is about 14884.1784455844. The cubic root of 221538768 is about 605.0852672207.

The spelling of 221538768 in words is "two hundred twenty-one million, five hundred thirty-eight thousand, seven hundred sixty-eight".