225721440 has 288 divisors, whose sum is σ = 900244800. Its totient is φ = 51480576.

The previous prime is 225721417. The next prime is 225721453. The reversal of 225721440 is 44127522.

It is a tau number, because it is divible by the number of its divisors (288).

It is a congruent number.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 493692 + ... + 494148.

It is an arithmetic number, because the mean of its divisors is an integer number (3125850).

Almost surely, 2^225721440 is an apocalyptic number.

225721440 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 225721440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (450122400).

225721440 is an abundant number, since it is smaller than the sum of its proper divisors (674523360).

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

225721440 is a wasteful number, since it uses less digits than its factorization.

225721440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 499 (or 474 counting only the distinct ones).

The product of its (nonzero) digits is 4480, while the sum is 27.

The square root of 225721440 is about 15024.0287539661. The cubic root of 225721440 is about 608.8695717514.

Adding to 225721440 its reverse (44127522), we get a palindrome (269848962).

The spelling of 225721440 in words is "two hundred twenty-five million, seven hundred twenty-one thousand, four hundred forty".