21396824 has 16 divisors (see below), whose sum is σ = 40230600. Its totient is φ = 10668672.

The previous prime is 21396803. The next prime is 21396827. The reversal of 21396824 is 42869312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21396827) by changing a digit.

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, 497 + ... + 6560.

Almost surely, 2^21396824 is an apocalyptic number.

It is an amenable number.

21396824 is a deficient number, since it is larger than the sum of its proper divisors (18833776).

21396824 is a wasteful number, since it uses less digits than its factorization.

21396824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7442 (or 7438 counting only the distinct ones).

The product of its digits is 20736, while the sum is 35.

The square root of 21396824 is about 4625.6701136160. The cubic root of 21396824 is about 277.6193745527.

The spelling of 21396824 in words is "twenty-one million, three hundred ninety-six thousand, eight hundred twenty-four".