225221021 has 4 divisors (see below), whose sum is σ = 228072000. Its totient is φ = 222370044.

The previous prime is 225220993. The next prime is 225221023. The reversal of 225221021 is 120122522.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 225221021 - 2¹⁰ = 225219997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (225221023) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1425371 + ... + 1425528.

It is an arithmetic number, because the mean of its divisors is an integer number (57018000).

Almost surely, 2^225221021 is an apocalyptic number.

It is an amenable number.

225221021 is a deficient number, since it is larger than the sum of its proper divisors (2850979).

225221021 is an equidigital number, since it uses as much as digits as its factorization.

225221021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2850978.

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 225221021 is about 15007.3655582850. The cubic root of 225221021 is about 608.4192891031.

Adding to 225221021 its reverse (120122522), we get a palindrome (345343543).

The spelling of 225221021 in words is "two hundred twenty-five million, two hundred twenty-one thousand, twenty-one".