221540424 has 128 divisors (see below), whose sum is σ = 653184000. Its totient is φ = 61311744.

The previous prime is 221540387. The next prime is 221540443. The reversal of 221540424 is 424045122.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a junction number, because it is equal to n+sod(n) for n = 221540394 and 221540403.

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 31 ways as a sum of consecutive naturals, for example, 1237567 + ... + 1237745.

It is an arithmetic number, because the mean of its divisors is an integer number (5103000).

Almost surely, 2^221540424 is an apocalyptic number.

221540424 is a gapful number since it is divisible by the number (24) 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 221540424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (326592000).

221540424 is an abundant number, since it is smaller than the sum of its proper divisors (431643576).

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

221540424 is a wasteful number, since it uses less digits than its factorization.

221540424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 387 (or 383 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 24.

The square root of 221540424 is about 14884.2340750205. The cubic root of 221540424 is about 605.0867748857.

Adding to 221540424 its reverse (424045122), we get a palindrome (645585546).

The spelling of 221540424 in words is "two hundred twenty-one million, five hundred forty thousand, four hundred twenty-four".