225721 has 2 divisors, whose sum is σ = 225722. Its totient is φ = 225720.

The previous prime is 225697. The next prime is 225733. The reversal of 225721 is 127522.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 156025 + 69696 = 395^2 + 264^2 .

It is a cyclic number.

It is not a de Polignac number, because 225721 - 2⁵ = 225689 is a prime.

It is a nialpdrome in base 12.

It is not a weakly prime, because it can be changed into another prime (225751) by changing a digit.

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 as a sum of consecutive naturals, namely, 112860 + 112861.

It is an arithmetic number, because the mean of its divisors is an integer number (112861).

2²²⁵⁷²¹ is an apocalyptic number.

It is an amenable number.

225721 is a deficient number, since it is larger than the sum of its proper divisors (1).

225721 is an equidigital number, since it uses as much as digits as its factorization.

225721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 280, while the sum is 19.

The square root of 225721 is about 475.1010418848. The cubic root of 225721 is about 60.8869176127.

It can be divided in two parts, 2257 and 21, that added together give a triangular number (2278 = T₆₇).

The spelling of 225721 in words is "two hundred twenty-five thousand, seven hundred twenty-one".