21306324 has 48 divisors (see below), whose sum is σ = 54440960. Its totient is φ = 6445440.

The previous prime is 21306317. The next prime is 21306343. The reversal of 21306324 is 42360312.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21306324.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8397 + ... + 10635.

Almost surely, 2^21306324 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21306324, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27220480).

21306324 is an abundant number, since it is smaller than the sum of its proper divisors (33134636).

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

21306324 is a wasteful number, since it uses less digits than its factorization.

21306324 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2320 (or 2318 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 21.

The square root of 21306324 is about 4615.8773813870. The cubic root of 21306324 is about 277.2274151489.

Adding to 21306324 its reverse (42360312), we get a palindrome (63666636).

The spelling of 21306324 in words is "twenty-one million, three hundred six thousand, three hundred twenty-four".