21306312 has 48 divisors (see below), whose sum is σ = 58007040. Its totient is φ = 7064928.

The previous prime is 21306301. The next prime is 21306317. The reversal of 21306312 is 21360312.

21306312 is a `hidden beast` number, since 2 + 1 + 30 + 631 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21306317) 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 11 ways as a sum of consecutive naturals, for example, 15393 + ... + 16719.

It is an arithmetic number, because the mean of its divisors is an integer number (1208480).

Almost surely, 2^21306312 is an apocalyptic number.

It is an amenable number.

21306312 is an abundant number, since it is smaller than the sum of its proper divisors (36700728).

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

21306312 is a wasteful number, since it uses less digits than its factorization.

21306312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1562 (or 1555 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 21306312 is about 4615.8760815256. The cubic root of 21306312 is about 277.2273631028.

Adding to 21306312 its reverse (21360312), we get a palindrome (42666624).

The spelling of 21306312 in words is "twenty-one million, three hundred six thousand, three hundred twelve".