21213124 has 12 divisors (see below), whose sum is σ = 37506364. Its totient is φ = 10497024.

The previous prime is 21213119. The next prime is 21213149. The reversal of 21213124 is 42131212.

It can be written as a sum of positive squares in 2 ways, for example, as 5846724 + 15366400 = 2418^2 + 3920^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21213098 and 21213107.

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, 26949 + ... + 27724.

Almost surely, 2^21213124 is an apocalyptic number.

It is an amenable number.

21213124 is a deficient number, since it is larger than the sum of its proper divisors (16293240).

21213124 is a wasteful number, since it uses less digits than its factorization.

21213124 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54774 (or 54772 counting only the distinct ones).

The product of its digits is 96, while the sum is 16.

The square root of 21213124 is about 4605.7707281192. The cubic root of 21213124 is about 276.8226001182.

Adding to 21213124 its reverse (42131212), we get a palindrome (63344336).

The spelling of 21213124 in words is "twenty-one million, two hundred thirteen thousand, one hundred twenty-four".