221520540 has 96 divisors (see below), whose sum is σ = 672888384. Its totient is φ = 54231040.

The previous prime is 221520539. The next prime is 221520577. The reversal of 221520540 is 45025122.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 39172 + ... + 44468.

It is an arithmetic number, because the mean of its divisors is an integer number (7009254).

Almost surely, 2^221520540 is an apocalyptic number.

221520540 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 221520540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (336444192).

221520540 is an abundant number, since it is smaller than the sum of its proper divisors (451367844).

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

221520540 is a wasteful number, since it uses less digits than its factorization.

221520540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5367 (or 5365 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 21.

The square root of 221520540 is about 14883.5661049360. The cubic root of 221520540 is about 605.0686714847.

Adding to 221520540 its reverse (45025122), we get a palindrome (266545662).

The spelling of 221520540 in words is "two hundred twenty-one million, five hundred twenty thousand, five hundred forty".