225691 has 4 divisors (see below), whose sum is σ = 226800. Its totient is φ = 224584.

The previous prime is 225689. The next prime is 225697. The reversal of 225691 is 196522.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 225691 - 2¹ = 225689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (225697) 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 in 3 ways as a sum of consecutive naturals, for example, 151 + ... + 688.

It is an arithmetic number, because the mean of its divisors is an integer number (56700).

2²²⁵⁶⁹¹ is an apocalyptic number.

225691 is a deficient number, since it is larger than the sum of its proper divisors (1109).

225691 is an equidigital number, since it uses as much as digits as its factorization.

225691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1108.

The product of its digits is 1080, while the sum is 25.

The square root of 225691 is about 475.0694686043. The cubic root of 225691 is about 60.8842200518.

The spelling of 225691 in words is "two hundred twenty-five thousand, six hundred ninety-one".