21812124 has 12 divisors (see below), whose sum is σ = 50894984. Its totient is φ = 7270704.

The previous prime is 21812113. The next prime is 21812143. The reversal of 21812124 is 42121812.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21812124.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 908827 + ... + 908850.

Almost surely, 2^21812124 is an apocalyptic number.

It is an amenable number.

21812124 is an abundant number, since it is smaller than the sum of its proper divisors (29082860).

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

21812124 is a wasteful number, since it uses less digits than its factorization.

21812124 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1817684 (or 1817682 counting only the distinct ones).

The product of its digits is 256, while the sum is 21.

The square root of 21812124 is about 4670.3451692568. The cubic root of 21812124 is about 279.4040214785.

Adding to 21812124 its reverse (42121812), we get a palindrome (63933936).

The spelling of 21812124 in words is "twenty-one million, eight hundred twelve thousand, one hundred twenty-four".