21003344 has 20 divisors (see below), whose sum is σ = 40765620. Its totient is φ = 10483200.

The previous prime is 21003343. The next prime is 21003349. The reversal of 21003344 is 44330012.

It can be written as a sum of positive squares in 2 ways, for example, as 1993744 + 19009600 = 1412^2 + 4360^2 .

It is a super-2 number, since 2×21003344² = 882280918364672, which contains 22 as substring.

It is a hoax number, since the sum of its digits (17) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003343) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15494 + ... + 16794.

It is an arithmetic number, because the mean of its divisors is an integer number (2038281).

Almost surely, 2^21003344 is an apocalyptic number.

It is an amenable number.

21003344 is a deficient number, since it is larger than the sum of its proper divisors (19762276).

21003344 is a wasteful number, since it uses less digits than its factorization.

21003344 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2318 (or 2312 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 17.

The square root of 21003344 is about 4582.9405407446. The cubic root of 21003344 is about 275.9070610552.

Adding to 21003344 its reverse (44330012), we get a palindrome (65333356).

The spelling of 21003344 in words is "twenty-one million, three thousand, three hundred forty-four".