21408124 has 24 divisors (see below), whose sum is σ = 39932928. Its totient is φ = 10018800.

The previous prime is 21408113. The next prime is 21408157. The reversal of 21408124 is 42180412.

It is a junction number, because it is equal to n+sod(n) for n = 21408095 and 21408104.

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 7 ways as a sum of consecutive naturals, for example, 1849 + ... + 6799.

It is an arithmetic number, because the mean of its divisors is an integer number (1663872).

Almost surely, 2^21408124 is an apocalyptic number.

It is an amenable number.

21408124 is a deficient number, since it is larger than the sum of its proper divisors (18524804).

21408124 is a wasteful number, since it uses less digits than its factorization.

21408124 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5025 (or 5023 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 22.

The square root of 21408124 is about 4626.8913970397. The cubic root of 21408124 is about 277.6682376743.

Adding to 21408124 its reverse (42180412), we get a palindrome (63588536).

The spelling of 21408124 in words is "twenty-one million, four hundred eight thousand, one hundred twenty-four".