225721020 has 96 divisors (see below), whose sum is σ = 734630400. Its totient is φ = 50713344.

The previous prime is 225720997. The next prime is 225721021. The reversal of 225721020 is 20127522.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (225721021) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 20226 + ... + 29334.

It is an arithmetic number, because the mean of its divisors is an integer number (7652400).

Almost surely, 2^225721020 is an apocalyptic number.

225721020 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 225721020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (367315200).

225721020 is an abundant number, since it is smaller than the sum of its proper divisors (508909380).

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

225721020 is a wasteful number, since it uses less digits than its factorization.

225721020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9187 (or 9185 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 225721020 is about 15024.0147763506. The cubic root of 225721020 is about 608.8691941098.

Adding to 225721020 its reverse (20127522), we get a palindrome (245848542).

The spelling of 225721020 in words is "two hundred twenty-five million, seven hundred twenty-one thousand, twenty".