21003244 has 24 divisors (see below), whose sum is σ = 38320128. Its totient is φ = 10061520.

The previous prime is 21003223. The next prime is 21003247. The reversal of 21003244 is 44230012.

It is a super-2 number, since 2×21003244² = 882272517047072, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003247) 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 7 ways as a sum of consecutive naturals, for example, 12477 + ... + 14059.

It is an arithmetic number, because the mean of its divisors is an integer number (1596672).

Almost surely, 2^21003244 is an apocalyptic number.

It is an amenable number.

21003244 is a deficient number, since it is larger than the sum of its proper divisors (17316884).

21003244 is a wasteful number, since it uses less digits than its factorization.

21003244 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1725 (or 1723 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 21003244 is about 4582.9296307057. The cubic root of 21003244 is about 275.9066231766.

Adding to 21003244 its reverse (44230012), we get a palindrome (65233256).

The spelling of 21003244 in words is "twenty-one million, three thousand, two hundred forty-four".