221520240 has 120 divisors (see below), whose sum is σ = 783141840. Its totient is φ = 55959552.

The previous prime is 221520227. The next prime is 221520283. The reversal of 221520240 is 42025122.

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5584 + ... + 21776.

It is an arithmetic number, because the mean of its divisors is an integer number (6526182).

Almost surely, 2^221520240 is an apocalyptic number.

221520240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221520240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (391570920).

221520240 is an abundant number, since it is smaller than the sum of its proper divisors (561621600).

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

221520240 is a wasteful number, since it uses less digits than its factorization.

221520240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16231 (or 16222 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 221520240 is about 14883.5560267028. The cubic root of 221520240 is about 605.0683983412.

Adding to 221520240 its reverse (42025122), we get a palindrome (263545362).

The spelling of 221520240 in words is "two hundred twenty-one million, five hundred twenty thousand, two hundred forty".