21218325 has 12 divisors (see below), whose sum is σ = 35081088. Its totient is φ = 11316400.

The previous prime is 21218321. The next prime is 21218333. The reversal of 21218325 is 52381212.

It is not a de Polignac number, because 21218325 - 2² = 21218321 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21218295 and 21218304.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21218321) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 141381 + ... + 141530.

It is an arithmetic number, because the mean of its divisors is an integer number (2923424).

Almost surely, 2^21218325 is an apocalyptic number.

21218325 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21218325 is a deficient number, since it is larger than the sum of its proper divisors (13862763).

21218325 is a wasteful number, since it uses less digits than its factorization.

21218325 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 282924 (or 282919 counting only the distinct ones).

The product of its digits is 960, while the sum is 24.

The square root of 21218325 is about 4606.3353112860. The cubic root of 21218325 is about 276.8452219111.

Adding to 21218325 its reverse (52381212), we get a palindrome (73599537).

The spelling of 21218325 in words is "twenty-one million, two hundred eighteen thousand, three hundred twenty-five".