225709821 has 24 divisors (see below), whose sum is σ = 343665504. Its totient is φ = 147996720.

The previous prime is 225709807. The next prime is 225709823. The reversal of 225709821 is 128907522.

225709821 is a `hidden beast` number, since 2 + 2 + 570 + 9 + 82 + 1 = 666.

It is not a de Polignac number, because 225709821 - 2¹¹ = 225707773 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (225709823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7210 + ... + 22436.

It is an arithmetic number, because the mean of its divisors is an integer number (14319396).

Almost surely, 2^225709821 is an apocalyptic number.

It is an amenable number.

225709821 is a deficient number, since it is larger than the sum of its proper divisors (117955683).

225709821 is an equidigital number, since it uses as much as digits as its factorization.

225709821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15303 (or 15291 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The square root of 225709821 is about 15023.6420684200. The cubic root of 225709821 is about 608.8591243950.

The spelling of 225709821 in words is "two hundred twenty-five million, seven hundred nine thousand, eight hundred twenty-one".