21806124 has 12 divisors (see below), whose sum is σ = 50880984. Its totient is φ = 7268704.

The previous prime is 21806123. The next prime is 21806143. The reversal of 21806124 is 42160812.

It is a tau number, because it is divible by the number of its divisors (12).

It is a junction number, because it is equal to n+sod(n) for n = 21806094 and 21806103.

It is not an unprimeable number, because it can be changed into a prime (21806123) 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, 908577 + ... + 908600.

It is an arithmetic number, because the mean of its divisors is an integer number (4240082).

Almost surely, 2^21806124 is an apocalyptic number.

It is an amenable number.

21806124 is an abundant number, since it is smaller than the sum of its proper divisors (29074860).

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

21806124 is a wasteful number, since it uses less digits than its factorization.

21806124 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1817184 (or 1817182 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 21806124 is about 4669.7027742673. The cubic root of 21806124 is about 279.3783999806.

Adding to 21806124 its reverse (42160812), we get a palindrome (63966936).

The spelling of 21806124 in words is "twenty-one million, eight hundred six thousand, one hundred twenty-four".