21306285 has 144 divisors (see below), whose sum is σ = 51123072. Its totient is φ = 7983360.

The previous prime is 21306283. The next prime is 21306289. The reversal of 21306285 is 58260312.

21306285 is a `hidden beast` number, since 2 + 1 + 30 + 628 + 5 = 666.

It is not a de Polignac number, because 21306285 - 2¹ = 21306283 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21306281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 495474 + ... + 495516.

Almost surely, 2^21306285 is an apocalyptic number.

It is an amenable number.

21306285 is an abundant number, since it is smaller than the sum of its proper divisors (29816787).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21306285 is a wasteful number, since it uses less digits than its factorization.

21306285 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96 (or 82 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 21306285 is about 4615.8731568361. The cubic root of 21306285 is about 277.2272459992.

Adding to 21306285 its reverse (58260312), we get a palindrome (79566597).

The spelling of 21306285 in words is "twenty-one million, three hundred six thousand, two hundred eighty-five".