21806324 has 12 divisors (see below), whose sum is σ = 38356164. Its totient is φ = 10847424.

The previous prime is 21806321. The next prime is 21806329. The reversal of 21806324 is 42360812.

It can be written as a sum of positive squares in 2 ways, for example, as 10368400 + 11437924 = 3220^2 + 3382^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21806293 and 21806302.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21806321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13049 + ... + 14624.

It is an arithmetic number, because the mean of its divisors is an integer number (3196347).

Almost surely, 2^21806324 is an apocalyptic number.

It is an amenable number.

21806324 is a deficient number, since it is larger than the sum of its proper divisors (16549840).

21806324 is a wasteful number, since it uses less digits than its factorization.

21806324 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27874 (or 27872 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 21806324 is about 4669.7241888574. The cubic root of 21806324 is about 279.3792541063.

The spelling of 21806324 in words is "twenty-one million, eight hundred six thousand, three hundred twenty-four".