218566225 has 12 divisors (see below), whose sum is σ = 273558384. Its totient is φ = 173216720.

The previous prime is 218566207. The next prime is 218566237. The reversal of 218566225 is 522665812.

It is not a de Polignac number, because 218566225 - 2⁵ = 218566193 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 38179 + ... + 43528.

It is an arithmetic number, because the mean of its divisors is an integer number (22796532).

Almost surely, 2^218566225 is an apocalyptic number.

218566225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

218566225 is a deficient number, since it is larger than the sum of its proper divisors (54992159).

218566225 is a wasteful number, since it uses less digits than its factorization.

218566225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81824 (or 81819 counting only the distinct ones).

The product of its digits is 57600, while the sum is 37.

The square root of 218566225 is about 14783.9854234235. The cubic root of 218566225 is about 602.3667858579.

It can be divided in two parts, 218566 and 225, that added together give a triangular number (218791 = T₆₆₁).

The spelling of 218566225 in words is "two hundred eighteen million, five hundred sixty-six thousand, two hundred twenty-five".