21243384 has 40 divisors (see below), whose sum is σ = 59502960. Its totient is φ = 7080912.

The previous prime is 21243361. The next prime is 21243403. The reversal of 21243384 is 48334212.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 15744 + ... + 17039.

It is an arithmetic number, because the mean of its divisors is an integer number (1487574).

Almost surely, 2^21243384 is an apocalyptic number.

21243384 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21243384 is an abundant number, since it is smaller than the sum of its proper divisors (38259576).

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

21243384 is a wasteful number, since it uses less digits than its factorization.

21243384 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32801 (or 32788 counting only the distinct ones).

The product of its digits is 4608, while the sum is 27.

The square root of 21243384 is about 4609.0545668282. The cubic root of 21243384 is about 276.9541644587.

Adding to 21243384 its reverse (48334212), we get a palindrome (69577596).

The spelling of 21243384 in words is "twenty-one million, two hundred forty-three thousand, three hundred eighty-four".