225206721 has 12 divisors (see below), whose sum is σ = 336516180. Its totient is φ = 144960480.

The previous prime is 225206713. The next prime is 225206747. The reversal of 225206721 is 127602522.

It can be written as a sum of positive squares in 2 ways, for example, as 152769600 + 72437121 = 12360^2 + 8511^2 .

It is not a de Polignac number, because 225206721 - 2³ = 225206713 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (225206321) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 431170 + ... + 431691.

It is an arithmetic number, because the mean of its divisors is an integer number (28043015).

Almost surely, 2^225206721 is an apocalyptic number.

It is an amenable number.

225206721 is a deficient number, since it is larger than the sum of its proper divisors (111309459).

225206721 is a wasteful number, since it uses less digits than its factorization.

225206721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 862896 (or 862893 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 27.

The square root of 225206721 is about 15006.8891180018. The cubic root of 225206721 is about 608.4064120043.

It can be divided in two parts, 22520 and 6721, that added together give a square (29241 = 171²).

The spelling of 225206721 in words is "two hundred twenty-five million, two hundred six thousand, seven hundred twenty-one".